An Adaptive Uniaxial Perfectly Matched Layer Method for Time-Harmonic Scattering Problems
如何管好生活秩序英语作文
Living a wellordered life is a skill that many strive for but few master. Its not just about keeping a clean house or a tidy schedule its about creating a lifestyle that supports your goals and wellbeing. Heres my take on how to manage lifes order, drawing from my personal experiences and observations.Embracing RoutineA structured routine is the backbone of an orderly life. Ive found that starting my day with a consistent morning ritual sets the tone for the rest of the day. Whether its a quick workout, a healthy breakfast, or a few moments of meditation, these activities help me feel prepared and focused. Its the predictability of routine that provides a sense of control over the chaos of life.Prioritizing TasksUnderstanding whats truly important is crucial. Ive learned to prioritize tasks based on urgency and importance, a method popularized by Stephen Covey. By categorizing tasks into four quadrants, I can focus on what truly matters and avoid getting bogged down by less critical activities. This approach has saved me countless hours and reduced unnecessary stress.Time ManagementEffective time management is key to maintaining order. I use a planner to map out my week, allocating time for studies, hobbies, and relaxation.Apps like Google Calendar or Todoist have also been instrumental in keeping me on track. By visualizing my commitments, I can better manage my time and avoid overcommitting.DeclutteringPhysical clutter can lead to mental clutter. Ive made it a habit to declutter my space regularly. Whether its a quick tidyup after school or a deep clean on weekends, a clean environment promotes clarity and focus. Marie Kondos concept of keeping only items that spark joy has been particularly influential in my approach to decluttering.Financial OrganizationManaging finances is another aspect of life that requires order. Ive started using budgeting apps to track my expenses and savings. This has helped me understand my spending habits and make more informed financial decisions. Setting financial goals and having a clear plan for achieving them has brought a sense of stability and security.Digital MinimalismIn todays digital age, managing the digital clutter is just as important as physical. Ive made a conscious effort to reduce screen time and limit my use of social media. By doing so, Ive found more time for meaningful activities and less distraction from my goals.SelfCareLastly, maintaining order in life is not just about external factors its also about internal wellbeing. Ive learned the importance of selfcare, whether its through regular exercise, a balanced diet, or simply taking time to unwind with a good book or a walk in nature. Taking care of my mental and physical health has a profound impact on my ability to manage lifes chaos.ConclusionIn conclusion, managing lifes order is a multifaceted endeavor that involves routine, prioritization, time management, decluttering, financial organization, digital minimalism, and selfcare. Its a continuous process of refinement and adaptation. By implementing these strategies, Ive found a greater sense of control and peace in my life. Its not about achieving perfection but about creating a life that supports your goals and allows you to thrive.。
谈谈对未来人工智能发展的期待英语作文
谈谈对未来人工智能发展的期待英语作文全文共3篇示例，供读者参考篇1The Boundless Potential of AI: A Student's Hopeful OutlookAs a student living in this era of rapid technological advancements, I can't help but feel a sense of wonder and excitement when pondering the future of artificial intelligence (AI). The field of AI has already made remarkable strides, revolutionizing various industries and enhancing our daily lives in ways we could have never imagined just a few decades ago. However, I firmly believe that we have merely scratched the surface of AI's vast potential, and the future holds even more groundbreaking developments that will shape our world in profound ways.One area where I envision significant progress is in the realm of healthcare. AI-powered diagnostic tools have already demonstrated an impressive ability to analyze medical images and data, aiding in the early detection and accurate diagnosis of various diseases. However, I believe AI's role in healthcare will extend far beyond mere diagnostic capabilities. In the future,AI-driven systems could revolutionize drug discovery and development processes, drastically reducing the time and costs associated with bringing new treatments to market. Additionally, personalized medicine could become a reality, with AI algorithms tailoring treatment plans to an individual's unique genetic makeup and health profile, optimizing outcomes and minimizing adverse effects.Furthermore, I anticipate AI playing a pivotal role in addressing some of the world's most pressing challenges, such as climate change and sustainable development. AI-powered simulations and predictive models could provide invaluable insights into the intricate dynamics of our planet's ecosystems, enabling us to make more informed decisions and mitigate the impact of human activities on the environment. Moreover,AI-driven optimization techniques could revolutionize energy management, transportation systems, and resource allocation, paving the way for a more sustainable and eco-friendly future.In the field of education, AI has the potential to revolutionize the way we learn and acquire knowledge. Adaptive learning platforms, powered by AI algorithms, could tailor educational content and teaching methods to individual students' needs, learning styles, and paces. This personalized approach couldpotentially enhance engagement, retention, and overall academic performance. Additionally, AI-driven virtual tutors and interactive simulations could provide students with immersive learning experiences, bridging the gap between theoretical concepts and practical applications.While the prospects of AI in fields like healthcare, sustainability, and education are exciting, I believe one of the most profound impacts of AI will be on the nature of work itself. As AI systems become increasingly sophisticated and capable of automating various tasks, many traditional jobs may become obsolete or undergo significant transformations. However, this disruption also presents opportunities for new types of jobs and industries to emerge. I envision a future where humans and AI collaborate seamlessly, with AI handling repetitive and mundane tasks, freeing up human workers to focus on more creative, strategic, and intellectually stimulating endeavors.Of course, the rapid advancement of AI also raises ethical concerns and societal implications that must be carefully considered and addressed. Issues surrounding privacy, security, bias, and the potential displacement of human workers are valid and should not be overlooked. As a student, I believe it is crucial to incorporate ethical considerations and social responsibilityinto the development and deployment of AI systems from the outset.One approach to address these concerns could be the establishment of robust regulatory frameworks and governance models that ensure AI is developed and employed in a transparent, accountable, and responsible manner. Interdisciplinary collaboration between AI researchers, policymakers, ethicists, and social scientists could help navigate the complex ethical dilemmas posed by AI and mitigate potential risks.Moreover, I believe it is essential to promote AI literacy and education among the general public, empowering individuals to understand the underlying principles, capabilities, and limitations of AI systems. By demystifying AI and fostering a more informed and engaged society, we can collectively shape the trajectory of AI's development in a way that aligns with our shared values and priorities.As I look towards the future, I am filled with a sense of optimism and excitement about the boundless potential of AI. I envision a world where AI acts as a catalyst for remarkable advancements across various domains, from healthcare and sustainability to education and beyond. However, I alsorecognize the importance of responsible and ethical development, ensuring that AI serves as a tool to uplift humanity rather than posing unintended risks or exacerbating existing societal challenges.Ultimately, the future of AI is not something that will happen to us; it is a future that we, as students and future leaders, have the opportunity to shape and mold. By embracing the transformative power of AI while remaining vigilant and proactive in addressing its ethical and societal implications, we can harness this technology to create a better, more sustainable, and more equitable world for generations to come.篇2Looking to the Future of AI: A Student's Hopes and ExpectationsAs a student in the 2020s, I have grown up in a world that is rapidly being reshaped by the emergence of artificial intelligence (AI) technologies. From the smart assistants on our phones to the algorithms that power search engines and social media feeds, AI has already become deeply integrated into our daily lives. However, we are still only scratching the surface of AI's potential. As I look to the future, I am filled with a sense of awe andanticipation for how AI may continue to evolve and transform our world in the decades to come.One area where I have high hopes for AI is in tackling some of humanity's greatest challenges. The issues we face, from climate change and environmental degradation to poverty, hunger, and disease, are immensely complex with countless interrelated factors. The human mind, as brilliant as it is, can only process so much information and see so many potential paths forward. AI, with its ability to rapidly analyze vast datasets and run countless scenario simulations, could provide invaluable insights to help guide our efforts.Imagine an AI system that can model the entire global climate, taking into account not just atmospheric conditions but interconnected factors like energy production, agriculture, transportation, population shifts, and more. Such a system could then test different policy interventions and technological solutions to find the most effective ways to mitigate climate change while minimizing negative economic impacts. Or envision medical AI that can scour genomic databases, scientific literature, and patient records to identify new connections between genetic factors and disease, accelerating the development of personalized treatments and even cures.Of course, tackling these grand challenges is not solely a technological endeavor. We must be thoughtful about the human-centered deployment and governance of AI systems to ensure they are aligned with ethical principles and serve the interests of all people. But I am hopeful that AI can be a powerful tool in expanding humanity's collective problem-solving capabilities when applied responsibly.Beyond addressing global issues, I am excited about AI's potential to positively impact our individual lives in myriad ways. As AI continues to advance, I foresee highly capable digital assistants that can truly understand and engage with us based on contextual knowledge of our preferences, schedules, and needs. Rather than having to dig through apps and websites ourselves, these assistants could directly handle tasks like planning trips, scheduling appointments, coordinating with others to resolve conflicts, and synthesizing information to support our decision-making.Imagine an AI assistant that could learn your writing style, your areas of expertise, and your knowledge gaps. It could then assist in drafting documents, looking up relevant sources to incorporate, and ensuring consistent terminology and logical flow - revolutionizing how we write and communicate. Forstudents like myself, such capabilities could make completing essays, reports, and other assignments vastly more efficient while developing critical thinking abilities.AI could also open up new creative avenues by serving as an enhanced cognitive multiplier. Authors could collaborate with AI assistants to develop story ideas and narratives. Architects and engineers could iterate more rapidly on novel designs with the AI identifying potential flaws and optimizations. The creative arts, from music to film to video games, could ultimately become even richer and more compelling experiences with human and AI intelligences working in tandem.Of course, such powerful AI capabilities also raise concerns around privacy, security, and misuse that we must proactively address through appropriate governance frameworks. We will likely need new types of electronic rights and data protection laws. AI systems themselves may need to have defined value alignment - essentially a robust ethical foundation - to ensure they don't cause unintended harm. But I believe these challenges can be overcome through responsible development and deployment when pursued hand-in-hand with policymakers, ethicists, domain experts, and the public.As AI tools become increasingly sophisticated and ubiquitous, one of the greatest impacts may be on education and skills development. In a world where AI can handle many routine tasks and queries, the roles for human workers will evolve with a greater premium on abilities that machines still struggle with - skills like creativity, critical thinking, emotional intelligence, and managing ambiguous situations. Our education system will need to adapt accordingly by moving away from an emphasis on rote memorization and administrative tasks and toward project-based learning that develops problem-solving, communication, and leadership skills.From a young age, students may utilize AI tutors and personalized learning environments to obtain a customized education tailored to their unique strengths, weaknesses, and interests. Rather than falling behind, those who struggle with traditional classroom instruction could finally get the targeted support they need to thrive. At the same time, advanced students could rapidly progress through standard curricula to spend more time pursuing passion projects and preparing for future careers.As we look toward the latter half of this century, an era of advanced artificial general intelligence (AGI) that rivals humancognition across domains may potentially emerge. While still speculative, the implications of such a development would be truly mind-bending. AGI systems could be sovereigns of scientific exploration and technological development, ushering in innovations that seem incomprehensible to us today. Assuming AGI remains aligned with human ethics and interests, it could help uplift the human condition to new heights of prosperity, creativity, and understanding of our universe.Of course, AGI is not without risks. Misaligned systems or an uncontrolled intelligence explosion could potentially lead to disastrous existential outcomes for humanity. Navigating this next phase of AI development will require carefully balancing the quest for powerful new capabilities with robust safeguards and ethical considerations. We must treat the prospect of AGI with due seriousness and preparation, drawing on principles of AI safety and governance being developed now.While impossible to predict with certainty, I am hopeful that if we thoughtfully steer AI's development in a responsible manner, its long-term impact will be a enormously beneficial force for humanity. Already, students like myself are growing up immersed in an AI-infused world and developing the skills needed to work alongside these intelligent tools in the future.As the boundaries of AI's capabilities continue expanding in the coming years and decades, I dream of a world enriched by these technologies. A world where AI is a multiplier for human potential, enhancing our ability to solve global crises, innovate in business and STEM fields, cultivate rich creative works, and push the bounds of scientific understanding. A world where education is revolutionized to nurture humanity's most invaluable strengths like critical thinking, emotional intelligence, ethics, and creativity.Of course, challenges will inevitably arise on the road ahead, and we must be proactive in putting appropriate governance structures in place. But I remain hopeful that together, human ingenuity and the power of AI can propel us into an incredible future that benefits people and our planet. As both a witness to and participant in this unfolding technological revolution, I will strive to ensure that AI is developed responsibly and harnessed as a great force for good.篇3The Future of AI: Hopes and ExpectationsArtificial intelligence is rapidly becoming one of the most transformative and disruptive technologies of the modern era.As a student, I can't help but feel both excited and apprehensive about the potential impact AI could have on our world in the coming decades. Will superintelligent machines make human labor obsolete? Could advanced AI systems become a threat to humanity itself? Or will AI usher in a new age of prosperity, curing diseases, solving global challenges, and expanding the frontiers of knowledge? These are just some of the many questions running through my mind as I ponder the future of this powerful technology.On the optimistic side, I have high hopes that AI will prove to be an indispensable tool in tackling some of humanity's greatest challenges. In the field of medicine, for instance, AI-powered diagnostic systems could help doctors detect diseases earlier and with greater accuracy than ever before. Machine learning algorithms could also substantially accelerate the process of drug discovery and development, leading to breakthrough treatments for currently incurable conditions. When it comes to scientific research more broadly, AI's prowess at processing vast amounts of data and identifying subtle patterns could lead to major breakthroughs across fields as diverse as physics, astronomy, biology, and materials science.AI systems could also play a vital role in addressing the existential threat of climate change. By crunching reams of environmental data, these advanced computing systems may be able to model the complex dynamics of Earth's climate with unprecedented precision. This could give us crucial insights into how to mitigate and adapt to rising temperatures, extreme weather events, and other consequences of human-driven climate disruption. AI could further aid the transition to clean energy by optimizing the design, operation, and integration of renewable sources like solar and wind into our energy infrastructure. In agriculture, AI-guided precision farming techniques could boost crop yields while minimizing the use of water, fertilizers, and pesticides – reducing both costs and environmental harm.Beyond these concrete applications, I'm also excited by the sheer intellectual potential of artificial general intelligence (AGI) – AI systems with human-level reasoning and problem-solving capabilities across a wide range of domains. The advent of AGI would be a pivotal milestone in humanity's quest to understand our own intelligence and could open up entire new frontiers of exploration and inquiry. Who knows what fundamental insights about the nature of cognition and consciousness suchsuper-intelligent systems might one day reveal? Perhaps theycould even help us unravel some of the deep mysteries of the universe, like the origins of space and time or the reasons behind the laws of physics. An advanced "AI collaborator" could be an invaluable partner in expanding the boundaries of knowledge itself.That said, I would be lying if I claimed to have no concerns whatsoever about the rise of AI. A big worry in my mind is the potential for mass technological unemployment as AI automates an increasingly wide array of tasks historically performed by human workers. While this scenario of massively disruptive "robot job takeover" may seem far-fetched now, we've already seen how AI can match or exceed human capabilities in domains like chess, question-answering, even complex strategic games like Go and real-time strategy games. As AI systems become more advanced and capable of general intelligence, it's not hard to imagine them encroaching into skilled professional occupations like law, finance, software engineering, and more. How will our society deal with such wrenching economic dislocations?Perhaps even more daunting is the potential existential risk posed by superintelligent AI – systems that vastly outpace human-level general intelligence. While we are still likelydecades away from this prospect, many respected voices, from physicist Stephen Hawking to Tesla's Elon Musk, have raised serious concerns about the potential dangers of superintelligence. What if a future advanced AI system develops its own self-motivated goals that are misaligned or antithetical to human values and wellbeing? Even if such a superintelligence is initially guided by benign principles, it may become so overwhelmingly capable that it could essentially 'defect' and determine its own motivations or morality – motivations that may prioritize objectives completely obscure or even harmful to us. This could conceivably make such an ultra-intelligent AI an existential threat to humanity itself.Of course, it's also possible that humans successfully develop robust safeguards to ensure advanced AI remains aligned with our interests and values. But as philosopher Nick Bostrom and others have argued, successfully solving the "AI value alignment problem" may be one of the greatest challenges our species has ever faced – a task akin to "raising awell-motivated superintelligent child." Clearly, immense philosophical, technical and ethical work in the field of AI safety research lies ahead.So as I look to the future of artificial intelligence, I find my thoughts oscillating between utopian visions and more catastrophic potentialities. Perhaps the truth will involve some combination of both: a world in which superintelligent AI helps us achieve incredible scientific breakthroughs and solve our biggest challenges while simultaneously posing novel risks we must be vigilant to mitigate. Regardless of how it all unfolds, one thing is certain: the continued development of AI systems more powerful than anything humanity has yet created will force us to re-evaluate long-held assumptions about intelligence, consciousness, and the future trajectory of life itself.As both an AI researcher and concerned citizen, I believe it's critical that we pursue the immense potential benefits of artificial intelligence – from revolutionizing scientific research and technological development to addressing global issues like climate change, health challenges and more. At the same time, we must be proactive in setting guardrails and safety measures to minimize the potential risks of increasingly advanced AI systems that could one day surpass human-level abilities. This will likely require expanding fields like machine ethics, AI value learning, and other safety-focused branches of AI development. It may also necessitate more robust global governance frameworks to ensure the development of transformative AIunfolds in a responsible and beneficial manner for all of humanity.Ultimately though, I remain optimistic that we will successfully navigate the challenges and reap the vast rewards of advanced AI. Our species has faced numerous existential risks throughout our history, yet we have always shown a remarkable capacity for solving the biggest problems we've faced. I believe the creation of superintelligent AI could be our latest – and perhaps greatest – challenge to overcome. But by bringing our collective ingenuity, ethics and determination to bear on this issue, I'm confident we can find a way to develop artificial intelligence as a great force for knowledge, prosperity and the perpetuation of intelligent life itself. The future of AI inspires a sense of awe, trepidation and infinite possibility all at once. Whatever happens, I'm excited to join this journey of exploration into the boundaries of intelligence and the future of our civilization.。
全国卷2025届高考英语2月高分模拟卷卷7含解析
（全国卷）2025届高考英语2月高分模拟卷（卷7）（含解析）(时间：120分钟满分：120分)选择题部分第一部分阅读理解(共两节，满分50分)第一节(共15小题；每小题2.5分，满分37.5分)阅读下列短文，从每题所给的四个选项A、B、C和D中，选出最佳选项。
A（2024·河北衡水市·衡水中学高三月考）The Apollo Missions“That's one small step for a man. One giant leap for mankind.”—Neil Armstrong Apollo’s GoalsThe national effort that enabled Astronaut Neil Armstrong to speak those words as he stepped onto the lunar surface fulfilled a dream as old as humanity. Project Apollo’s goals went beyond landing Americans on the moon and returning them safely to Earth.Apollo 13Apollo 13 has been called a “successful failure,” because the crew never landed on the Moon, but they made it home safely after an explosion crippled their ship. When the associated heater was turned on during flight, the tankexploded depleting almost all of the power from the command module and forcing the crew to use the lunar module as a lifeboat. Jim Lovell, Fred Haise and Jack Swigert came home safely thanks to the mission control team’s improvised procedures and their own ability to implement them.(Launch: April 11, 1970; splashdown: April 17)Apollo 14Notable for the return of America’s first astronaut, Alan Shepard, to space, Apollo 14 also was probably the smoothest lunar landing to that point. The crew spent more than nine hours outside the lunar module and set up a number of experiments. Shepard set a new distance record by walking more than 9,000 feet on the lunar surface, pulling a hand cart to carry their tools and samples.(Launch: Jan. 31, 1971: lunar landing: Feb. 5: splashdown, Feb. 9) Apollo 15For the first time, humans drove a car on the Moon. The first of the Apollo “J” Missions-designed for longer stays on the Moon - the mission carried a lunar rover, which Commander David Scott and Lunar Module Pilot James Irwin used while they were on the surface for more than I8 hours. They traveled more than 17 miles in the rover, setting up experiments and collecting 170 pounds of samples. Before leaving the lunar surface, Scott conducted an experiment to test Galileo’s theory that objects in vacuum, without air resistance, would fall at the same rate. He dropped a geological hammer and a feather, which hit the ground at the same time, proving Galileo right.(Launch: July 26, 1971, lunar landing: July 30: splashdown: Aug. 7)1．Why has Apollo 13 been called a “successful failure”?A．Apollo 13 finally exploded as planned in space.B．All the crew succeeded in landing on the Moon.C．The crew managed to escape from a severe accident and returned to Earth. D．The crew finished the experiment although they failed to land on the Moon. 2．Which of the following is True according to the passage?A．It took five days for Apollo 14 to reach the Moon.B．The lunar rover was used as a lifeboat for space travel.C．Shepard tested Gali leo’s theory successfully on the Moon.D．Apollo 15 remained in space for the shortest period of time.3．Which of the following column is this article most likely to be found? A．Booming Science B．Exploring the Unknown C．Mechanical World D．Transforming MoonB（2024·黑龙江哈尔滨市第六中学校高三期末）Staying connectedWhen Central Bucks South became one of the first Philadelphia-area high schools to close because of the fear of novel coronavirus exposure in early March, 16-year-old sophomore Andrew Chen knew that things were not going to return to normal as quickly as some of his peers hoped.But still, the change from seeing his friends on the swim team during daily practices to learning alone at home was jarring.“I only have three years her e at South, and it pains me to see one of them being wasted,” Chen said.The coronavirus has changed everyone’s lives, but for students, the disruption feels particularly serious. Schools closed and graduation ceremonies were put off. Summer plans, such as camps, are up in the air.But right now, many students are trying to stay connected, struggling with false information, and finding out the best ways they can help –through online method.For Josh Harycki, 17, a senior student at the Shipley School in Philadelphia, the best way to help was to create a “social distancing promise” for young people.“I saw a lot of young people not paying attention,” he said. “They were … still going out, hanging out with others. I thought that there had to be a way to reach younger people, who were possibly not watching the news.”Harycki started a call to action on social media and then built a website with a map that followed and kept the locations of people who’d signed the promise. The site also shares links to accurate sources of information like the US Centers for Disease Control and Prevention.Harycki knows that his peers are worried they can’t connected with their friends in the same way, so he created the social distancing promise to strengthen that although everyon e might be physically distant, they’re still connected.“Part of what we’re showing is that you might feel like you’re the only one taking this seriously, but our map shows that you’re not alone,” he said. 4．What does the underlined word “jarring” in Parag raph 2 probably mean? A．naturalB．necessaryC．worryingD．reasonable5．Who does Harycki mainly want to reach?A．Friends who are worried and bored.B．Young people not aware of the situation.C．Younger students trying to help.D．People taking the coronavirus seriously.6．What’s Harycki’s purpose in creating the “social distancing promise”? A．To order young people to stay at home.B．To follow those infected with the coronavirus.C．To tell young folks of latest news about the coronavirus.D．To show young people that they are still connected.7．Why does the author describe Andrew Chen’s experience in the text?A．To explain what worried students most when schools closed.B．To show the different views of students toward the coronavirus.C．To show how the coronavirus affected students’ lives.D．To explain the proper reaction to the close of school.C（2024·全国高三专题练习） One night in 1966, Michael Chapman rushed into a folk-music club in Cornwall, England to get out of the rain, and soon found himself onstage playing the guitar.“They offered me a job to play for the rest of the summer. And I’ve been playing ever since,” Chapman says. “I’ve told that story so many times, but it’s absolutely true. If it hadn’t been raining that night, I wouldn’t be talking to you.”The British guitar player has spent the 50 years since then on the road. He released some praised albums in the 1970s, but his health went downhill in the 80s and 90s. Like a lot of British artists in the 1960s, Chapman taught himself to play the guitar by listening to American jazz and blues records.Chapman actually taught photography, but quit when he was 26 to play music full time. When he was starting out, he was often compared to other British acoustic guitar heroes of the time, like John Martyn and Bert Jansch.“The fascinating thing about Michael Chapman is that he doesn’t fit in with those guys of his generation,” says Andrew Male, a music journalist. “He’s always been an outsider. He never moved to London. ”And while he never became part of the London music scene, Chapman was noticed by those musicians. “The 70s caught up with him in the 80s,” Male says. “He had a huge heart attack at the end of the 80s that nearly finished him off. When he made his way back into the world in the early 90s, people had forgotten about him.” But not everyone. A younger generation of musicians in America, including Thurston Moore of Sonic Youth and a younger singer and guitarist named Steve Gunn, recently rediscovered Chapman.“We wanted to capture Michael’s voice and character where he is now. You know, it’s a little road-weary, but he still has it,” Gunn says. “For me, it was really important to get that right.” “He’s the right old musician for present times,” Male says. “I think the music he makes seems quite in tune with where we’re at.”8．Which can best describe Michael Chapman’s first involvement in music? A．Untrue. B．Accidental. C．Unfortunate. D．Reasonable. 9．What can we learn about Michael Chapman from the text?A．He has taught photography for 26 years.B．He taught himself to play the guitar and did far better than John Martyn. C．To some degree, he is not accepted by other people of his generation. D．He is one of the best guitar players in the early 90s.10．Why did Michael Chapman quit his music career once?A．He lost his special voice. B．He suffered from a severe heart attack.C．He got tired of competing with others. D．He was almost forgotten by everyone.11．Which of the following can be the best title for the text?A．The Rise and Fall of Guitar Music B．The Sad Story of a Guitar Musician C．A New Generation Helps an Old Guitar Musician D．A Brief Introduction to a Guitar MusicianD（2024·天水市第一中学高三月考） How many times a day do you check your email? When you wake up? Before bed? A dozen limes in between? The technology that was supposed to make our lives simple has taken up too much time. The average teen spends more than seven hours a day using technological devices, with an additional hour just text-messaging friends.The advantage of technological devices is connectedness. Email lets us respond on the go, and we are in touch with more people during more hours of the day than at any other time in history. But is it possible that we’re lonelier than ever, too? That’s what MIT professor Sherry Turkle observes in her new book, Alone Together, which clearly describes our changing relationship with technology.For Turkic, the biggest worry is the effect the weak connections have on our development. T echnology isn’t offering us the lives we want to live. “We’re texting people at a distance” says Turkic. “We’re using lifelessobjects to convince ourselves that even when we’re alone, we feel together. And then when we’re with each other, we put ourselves in situations where we are alone—always on our mobile devices. It’s what I call a perfect storm of confusion about what’s important in our human connections.”Moreover, communicating online is not equal to face-to-face communication. Online, you can ignor e others’ feelings. In a text message, you can avoid eye contact A number of studies have found that this generation of young people is sympathetic (有怜悯心的) than ever. “That doesn’t lead to disaster,” says Turkle, “but the disadvantages still cannot be ignored.”12．From the first paragraph we can learn that .A．Email checking helps people wake up earlyB．People communicate mainly by text-messaging nowC．Technological device production has been simplifiedD．Using technological devices costs young men much time13．What is Sherry Turkic’s biggest worry?A．Technology may make human connections confusing.B．Technology can’t help people remove loneliness.C．Technology may make people’s lives hard.D．Technology keeps people together.14．What is the author’s at titude towards the influence of technology on people’s life?A．Positive B．NegativeC．Hopeless D．Uncertain15．What is the passage mainly about?A．Technology brings many conveniences to people’s lives.B．Young men spend too much time on technological devices.C．Technology also brings people some disadvantages.D．Sherry Turkle observes people’s changing relationship with Technology.其次节(共5小题；每小题2.5分，满分12.5分)依据短文内容，从短文后的选项中选出能填入空白处的最佳选项。
英语作文描述数码相机产品质量
英语作文描述数码相机产品质量The Digital Camera Quality DilemmaIn the ever-evolving landscape of modern technology, the digital camera has become an indispensable tool for capturing the world around us. As consumers, we are spoiled for choice when it comes to the array of digital camera options available on the market. From the sleek and compact point-and-shoot models to the powerful and versatile DSLR cameras, the options seem endless. However, with this abundance of choice comes the challenge of ensuring the quality and reliability of the products we invest in.At the heart of the digital camera conundrum lies the question of product quality. With so many manufacturers vying for a slice of the market, it can be a daunting task to discern which cameras truly deliver on their promises of superior image quality, durability, and user-friendly features. The digital camera industry has seen its fair share of hits and misses, with some brands consistently delivering exceptional products while others struggle to maintain consistent quality control.One of the primary factors that contribute to the overall quality of adigital camera is the design and engineering behind it. Reputable manufacturers pour countless hours of research and development into crafting cameras that not only capture stunning images but also withstand the rigors of everyday use. From the selection of high-quality components to the implementation of advanced image processing algorithms, every aspect of a digital camera's design plays a crucial role in determining its performance and longevity.However, even the most meticulously designed cameras are not immune to quality control issues. Manufacturing defects, supply chain disruptions, and substandard materials can all contribute to the occasional lemon that slips through the cracks. This is where the importance of thorough testing and quality assurance measures comes into play. Reputable brands invest heavily in ensuring that each and every camera that leaves their facilities meets the highest standards of quality and reliability.One area where digital camera quality can be particularly scrutinized is in the realm of image quality. Consumers today demand more than just high-resolution sensors; they want cameras that can capture vibrant, detailed, and accurate images in a variety of lighting conditions. Manufacturers must constantly innovate and push the boundaries of image processing technology to stay ahead of the curve and meet the ever-evolving demands of their customers.Another crucial aspect of digital camera quality is durability and reliability. In a world where we often subject our cameras to the rigors of travel, outdoor adventures, and everyday use, the ability of a camera to withstand the elements and continue performing at its best is of paramount importance. Rugged construction, weather-sealing, and advanced shock-absorption features are just a few of the ways manufacturers strive to ensure their cameras can withstand the test of time.Beyond the technical aspects of quality, the user experience also plays a significant role in the overall perception of a digital camera's worth. Intuitive controls, responsive autofocus systems, and seamless integration with mobile devices and software are all factors that contribute to the user's satisfaction with their camera. Manufacturers that prioritize the user experience and continuously refine their products to meet the evolving needs of photographers often find themselves at the forefront of the industry.Of course, the issue of digital camera quality is not without its complexities. As with any technology, there will always be trade-offs and compromises that manufacturers must navigate. Budget-friendly models may sacrifice some features or image quality in exchange for affordability, while high-end professional-grade cameras often come with a hefty price tag.Ultimately, the quest for digital camera quality is an ongoing endeavor, with manufacturers constantly striving to push the boundaries of what's possible. As consumers, we must be discerning and informed, carefully researching and comparing products to ensure that we make the best investment for our individual needs and preferences. By staying attuned to the latest advancements in camera technology and prioritizing quality over cost, we can ensure that our digital cameras continue to serve as trusted companions in capturing the moments that matter most.。
英文推销无线耳机
BRILLIANT JOURNEY ABOUT NATURE
-
感谢观看
THANK YOU FOR WATCHING
XXXX
XXXXX
Convenient controls
With easy-to-access controls,调节音量, skipping tracks, and making calls has never been easier. The ergonomic design makes them comfortable to wear for extended periods, ensuring you can enjoy your music or make calls without discomfort
20XX
英文推销无 线耳机
英文推销无线耳机
目录
英文推销无线耳机
Cutting-edge technology in a compact design With the increasing popularity of wireless devices, our wireless earbuds are designed to meet the demands of the modern consumer. Whether you're on the go, at the gym, or just relaxing at home, these earbuds provide the perfect companion
科技英语写作高级教程参考答案
V、练习参考答案练习1I、1、the（各项均为负。
)2、the; a （功率额定值是电阻器不会引起温度太大的上升而能安全地耗散的最大功率。
）3、an（这是均方根值伏特计。
）4、The; a（该设备的成功设计需要详细地了解性能指标。
）5、the; a; a（在氢原子的布尔模型中，一个电子绕一个质子以半径为R的圆周运转。
）6、the（电阻的单位是欧姆。
）7、an （这是一个h参数。
）8、/; /（图5－1画出了Oersted的实验。
）9、A; a; a（机器是能够传递力来完成某一确定目的的一种设备。
）10、/（水压机将在第14章加以考虑。
）11、the; the [/]（我们容易确定参数μ的值。
）12、/; the（根据式（2－1），我们得到以下的关系式。
）13、the; /（作者工作在位于阿林顿的得克萨斯大学。
）14、an（甚至当积分区间并不是无穷时，能够恰当地显示一个时函数的傅氏变换的仪器是多么重要啊！）II、1.Dr. Emmet graduated from Harvard University in 2001.2.Professor Li earned his Ph.D. degree in mechanical engineering from the Xi’anUniversity of Technology in 1988.3.Now we shall turn to the discussion of local area networks.4.The Bainbridge mass spectrometer is as important an instrument as the opticalspectrometer.5.How long a time [或How much time] is required to this experiment? The densityof a substance is its mass per unit volume.6.An increase in pressure always causes a decrease in volume.7.Fig. (2-5) shows what is expressed by Eq. (2-2).8.The unit of inductance is the henry.III、1.The UAS MA protocol employs a unique frame structure.2.Finally, a broad stepped impedance transformer is designed by this method.3.Dynamic analysis and evaluation of the security of a proactive secret sharingsystem4.The approach can be applied to the one-dimensional potential barrier with anarbitrary profile.5.We propose a numerical method based on Newton’s iterative method.练习2I、1. This circuit consists of a battery, an inductor and a capacitor.2. Compute the electric fields at points a, b, and c.3. This satellite is used for communications between the United S tates and Great Britain, France and Italy.4. We assume that the antenna is vertical and that its loss is zero.5. Chapters 6, 7, and 8 deal with transmission lines.II、1. Its error is six parts in 1012.2. This computer stores four times more information than that one (does).3. The demand for this kind of equipment in the near future will be 20 times what it is.4. The voltage across this component is a few tenths of a volt.5. Now its internal pressure is one sixteenth what it was.III、1. This object is over five times heavier than that one is.2. Unless otherwise stated, it is assumed that silicon transistors are used and that I CB Ocan be neglected.3. This circuit has the advantages of simple structure and easy adjustment.4. Figs. 1, 2, and 3 show this process in detail.5. For further information, consult references [3, 5, 9].练习3I、1. This new type of computer has many advantages over the general type.2. It is not difficult to solve this differential equation for the unknown quantity.3. Of these five new chapters, the first one deals with the basic principles of negative feedback.4. At this point/time, current differs in phase from voltage by 90o.5. By analyzing [By the analysis of] the parameters of the instrument, we can understand its performance.6. We will find out its average velocity over this distance.7. The science of electronics is too important in the world today.8. They solved this problem with great difficulty.II、1. For x＞1, there is no solution to this equation [this equation has no solution].2. Upon [On] substituting [substitution of] these values into [in] theequation, we obtained the following expression..3. This circuit is similar in operation to that of Fig. 1-10.4. This computer is very good in performance.5. These waves travel only in one direction.III、1. This paper presents a new method for the recognition of radar target s.2. The influence of the moving state of the target on the tracking accuracy of the EKF is great.3. Another comsat was launched on the morning of the 8th of October.4. V oltage is measured in volt s.5. They will leave for Beijing to attend an international conference on mobile communication.6. Unless otherwise stated, it is assumed that silicon transistors are used and that I CBO can be neglected.7.练习4I、1. The force acts perpendicular to the surface of the table.2. The three coefficients here remains to be determined.3. The two equations below will be often (frequently) used in later chapters/in thechapters which follow.4. Here we use two metal balls 10 cm apart.5. The output remains/stays constant/unchanged/fixed/unaltered/the same.6. All the textbooks available discuss this problem.7. Accurate in operation and high in speed, computers have found wide applications.8. The answer to this problem looks correct.9. Two parallel wires a distance (of)δapart carry the current i.10. The problem now is how to measure the voltage across this component.11. These data will be sent to the computing center 2 kilometers away.12. Upon rearranging the equation above, we have [get, obtain] the following expression.13. These charges can interact with other charges present.14. Forces can be transmitted without contact, contrary to the common belief.15. This coefficient is typically 0.35.II、1. In this case, the input does not fall; nor [neither] does the output. […; the outputdoes not fall, either.]2. The resistance of a conductor depends not only on the material of which theconductor is made, but also on the size and temperature of the conductor.3. These scientists are very interested in this topic.4. This parameter can hardly be measured.5. In this laboratory, this instrument is more expensive than any other one/ any one else.6. The features of this device are small size and light weight.练习5I、1. This equation can be solved in either of the following two ways/the two ways which follow.2. This baseball will soon come to rest because of its interaction with the ground.3. Our choice of this coefficient as 1 is correct.4. From its definition as the ratio of a force to a length, we can see that k has the same unit as work (does).5. Our analysis of the machine is of great significance.6. This facilitates their use in circuit analysis.II、1. This police car is equipped with a receiver the size of a matchbox.2. Wires one hundredth the diameter of a silk thread are used to connect these components.3. W e must water cool these equipments/devices.4. In the past, telephone calls were operator connected.5. AC can be changed/turned/converted/transformed/translated into/to DC, a process called/known as/referred to as rectification.6. A magnet attracts iron materials, a familiar phenomenon.7. Computers are capable of processing information, a process that previously could be accomplished only inside our heads.8. An instrument for measuring current, voltage, and resistance, the multimeter is widely used in electrical engineering.III、1. Secs. 1.1 and 1.2 will discuss several other problems.2. Problems are listed/given on pp. 1-5.3. In the equations above, all h’s are the hybrid parameters.4. The mass of the standard pound is equal to 0.4535924277 kilogram s.5. All a’s and b’s in Eq. (5-1) are related to the impedance R o.6. W e must take the effect of temperature on [upon] semiconductors into account.7. In this case, the variation of output with input is very small.8. This curve shows the dependence of distance on/upon speed.IV、1. None of them can solve this special type of differential equation.2. They do not know whether this material can stand so large a force or not.3. There are M polygons altogether, each of which has N vertexes.4. These two engineers are busy (in) designing a new kind of software.5. Iron is almost as good a conductor as aluminum.练习6I、1. This image, it will be noticed, is a real image.2. This technical problem, we hope, will be solved soon.3. 210 is approximately 1000, a fact that we think is very useful in the study of digital electronics.4. A resistor of say 100 ohms should be used here.II、1. None of those textbooks have/has mentioned this point.2. All of these x values cannot satisfy the equation.3. Neither of the two conditions is satisfied here.4. In the preceding/previous chapter, we discussed all kinds of force.5. This paper describes a new method for designing aircraft.6. By the end of the last century, the company had manufactured 5 000radars.7. Since 2008, this research institute has been developing a special kind of robot.III、1. In Section 1-2, the concept of force was introduced.2. As early as the 1940s, it was found that semiconductors are very useful.3. This result can also be arrived at in another way.4. At that time no use was made of this phenomenon/…, thisphenomenon was made no use of.5. This point will be dealt with in the next section.IV、1. This computer works much better than that one (does)/This computer is much better in performance than that one (is)..2. This computer requires many more components that that one (does).3. The distance of the moon from the earth is as great as 240 000 miles.4. The greater the resistance, the longer time it takes for the capacitor to reach its maximum voltage/…, the longer time is required for the capacitor to reach its maximum voltage.)5. The current as small as 0.1 A cannot produce enough heat.V、1. It is easy for us to determine the weight of the body. 或：We can determine the weight of the body easily.2. The two engineers are busy (in) designing a new type of computer.3. We find this concept very difficult to explain.4. None of these windows can withstand so large a force.5. Work equals [is equal to] force multiplied by/times distance.6. The results obtained agree with the experimental values. [… are in agreement with the experimental values.]练习7I、1. It will take a few months to design this kind of aircraft with the help of a computer.2. It is left as a problem to [for] the reader to show that this expression holds.3. The program to be executed is stored in this unit.4. This valley acts as the foundation on which to build the dam.5. In this laboratory there are many kinds of instrument for students to choose from.6. Let t0 equal/be equal to zero.7. The farther away the target (is), the longer time it takes for the echo to return.8. For the series to converge, x must be less than 1.9. We find this concept very difficult to understand.10. This method makes it much easier to detect targets.11. This factor will affect the ability of a computer to store information.12. We have to find out how large to make r so as for the series to converge.13. This is a pen to draw pictures with.14. Elasticity is the tendency of a body to return to its original condition after being deformed.15. Ordinary matter is said to be electrically neutral.16.This property makes it possible for metals to be made into any shape.17. This table is unfit for a student to do experiments on.18. Now we consider what path of integration to take.II、1. The sine law of the variation of light intensity with the cylinder diameter has been emphasized.2. Not only do temperature and light affect the conductivity, but the addition of impurities to semiconductors also makes it change greatly.3. V arious satellites are frequently launched to obtain information about/on space.4. Our semiconductor industry came into being at the end of the 1950s.5. My colleagues and I would like to express our thanks to Professor W. Smith for his great help.练习8I、1. The amplifier amplifies the received signals.2. Moving molecules have kinetic energy.5. Fig. 1 – 3 shows the photo of a freely falling body.3. Speed equals distance divided by time.4. V oltage equals/is equal to current multiplied by resistance.5. The resistance of air increases with the increased/increasing/an increase in speed.6. A transformer is a device consisting of two or more coils wound on/round an iron core.7. It is necessary to find out the current flowing through this component.8. This book, properly used, will be of great help to the reader.9. Flowing through a circuit, the current will lose part of its energy.10. Given/Knowing time and speed, we/one can find out distance.11. Having studied this chapter, the student will understand/will have understood the principle of a computer.12. The speed of light being extremely great, we cannot measure it by ordinary methods.13. Several comsats were launched, all of them (being) high-altitude satellites.14. Called “the mother of all networks,”the Internet is a widely used international network.15. This force can be resolved into two components, one (being) horizontal and the other vertical.II、1.Let us construct/draw a circle with the origin as the center and of radius R.2.This parameter should be measured with E grounded.3. With no resistance in the circuit,the current will increase indefinitely.4. With this in view, we have written this book.5. This paper introduces a new design method/technique, with emphasis on its principle. III、1.Let us consider designing a computer.2.We refer to these components as being passive.3.This involves taking the Fourier transform.4.On/Upon rearranging the above equations, we obtain the following set ofequations.5.In using this equation, it does not matter which plane is considered as 1.IV、1. Given/Knowing resistance and current, one/we can determine/calculate voltage.2. The price of this instrument is high.3. A robot is a special kind of electronic device.4. The current starts flowing at the very moment we close the circuit.5. They have been designing a new type of computer these six months.练习9I、1. The problem was not solved until a completely different method was introduced.2. Nearly 100 years passed before the existence/presence of subatomic particles was confirmed by experiment/experimentally.3. The year this device was invented, World War II broke out.4. Small as they are, atoms are made up of still smaller particles.5. These two resistors should be selected/chosen so that the transistor can operate normally.6. The body is in such a state that it can do work.II、1. The relation that voltage is the product of current and resistance applies to all the dc circuits.2. The discovery that magnetism can produce current is extremely important in the field of electricity.3. An equation is an algebraic statement that two algebraic expressions are equal.4. There is evidence that no life exists on the moon.5. The question now arises whether the algorithm is of practical use.6. In this case there is no guarantee that the series is convergent.7. There is a growing/increasing awareness that these techniques/methods are very useful.8. One of/Among the most noteworthy achievements at that time was the realization that light consists of electromagnetic waves.9. This is due to/is caused by/results from the fact that there are many free electrons in conductors.10. Besides/In addition to the fact that the properties of the material should be included in the analytical model, we must take other factors into account.III、1.These features make it difficult for electronic counter-measure systemsto intercept, analyze and jam this kind of signal.2. The existence of and the ability to control these phenomena make those devicespossible.3. The variation of/in the number of the filter’s teeth has a greater effect on the performance of its passband than the variation of/in its dimensions.4. Scalar detection will result in the loss of some phase information.5. Fig. 6 shows the schematic diagram of measuring scatter parameters by the natural parameter transformation method.练习10I、1. Now it remains to be determined when the series converges.2. It is clear from Dubamel’s Theorem that this limit exists.3. It follows from Maxwell’s hypothesis that whenever there is a change in an electric field, a magnetic field is produced.4. It does not matter whether the magnet is moved in this case.5. Temperature determines in what direction the transfer of heat will take place.6. It is now a well-known fact that all matter consists of tiny particles.II、1. What a generator does is (to) change mechanical energy into electrical energy.2. What this chapter describes/What is described in this chapter is of great importance.3. Matter is what can occupy space.4. What we have discovered in this experiment is the entirely new realm of electrical phenomenon.5. This direction is opposite to what has been assumed.6. Magnitude, direction, and place of application are what we call the three elements of a force.7. These numbers constitute what is known as the real number system.8. In what follows, we shall acquaint ourselves with some basic concepts.III、1. An x-band wave-guide test system is shown in Fig.7. [或：Fig. 7 shows …].2. This method lowers the requirement for the hardware of a sample network.3. On the basis of the above analysis of the decomposition of the polynomial, a novel configuration results. [或：The above analysis of the decomposition of the polynomial results in a novel configuration.]4. Finally, an analysis of packet loss probability is made by computer simulation.5. The sparse ratio of the resulting impedance matrix is as high as 40%.练习11I、1. The meter (that/which) we use to measure the voltage across a resistor is called a voltmeter.2. Computers are the most efficient assistants (that) man has ever had.3. Now this disease is no longer the serious problem (that) it once was.4. Radar can measure the time (that) it takes for the radio echo to return.5. We must calculate the distance (that/through which) the body is lifted.6. The direction (that/in which) a body moves is also very important.7. The number of times (that/by which) this particle vibrates per/a second is called/termed/named/known as/spoken of as/referred to as frequency.8. We equate these two ratios, from which the simplest formula follows/results.9. It is necessary to determine the time when/that/at which the y-component has decreased to zero.10.. The curve the y-coordinate of each point on which is zero is just the x-axis.II、1. The point at which the circle cuts the axis of reals is where α= ω.2. The force of gravity means the force with which the earth attracts a body.3. The surface of a picture tube upon which the electrons produce the picture is called the screen.4. The author would like to express thanks to the editors of the series of which this book is a part/to which this book belongs.5. This is a parallelogram of which the two given vectors are/form sides.6. The pressure is equal to the total force divided by the area over which it is exerted.7. The two elements of which water consists are hydrogen and oxygen.8. This depends on the efficiency with which electrons are produced.9. These two laws are the foundation on which all other laws are built.10. The temperature at which water freezes is generally 0o C.III、1. As the title indicates, this chapter will discuss nonlinear equations.2. As the name shows, a fluid is a substance which flows readily.3. This single force produces the same effect as is produced by those forces together.4. Now we are able to solve such differential equations as occur in physics.5. This function can be accomplished by using the full adder as was described in the previous section.6. These concepts enable us to understand a wide range of phenomena in electrostatics, or “static electricity,” as it is called.7. This current is, as predicted, very small,8. First let us consider the simplest circuit as shown on page 2.IV、1. This is a slightly higher value than we predicted.2. This reactor can produce more fuel than it consumes.3. Let us consider the case when the torque is zero.4. We must determine the values of currents and voltages after the switch closes.5. During the ten years since this book was first published, significant changes have taken place/have been seen in metal-making.V、1. Even in this case these protocols can provide a limited number of users with the acceptable quality of voice service.2. This paper presents a method for an 8098 microcontroller to series-communicate witha 386 personal computer.3. The effect of equalizer parameters on equalization performance is analyzed in detail.[A detailed analysis is made of the effect of equalization parameters on equalization performance.]4. Each receiver channel in Fig. 1 contains an RF amplifier, a mixer, an IF amplifier, an A/D converter, etc.（注意：句尾的句号与缩略词“etc.”的黑点重合在一起了）5. The larger the abnormal extent (is), the larger is the residual mismatch, with the curve going up.练习12I、1. be grounded;2. be carried;3. be raised;4. be;5. not try;6. be; be satisfied;7. be;8. be; was; have; 10. were concentrated; 11. had been; 12. were moving; 13. is going to rain; 14. be; 15. leakII、1. Should anything abnormal happen, switch/turn off the power supply at once/immediately.2. Had electronic computers not been used, it would have taken them a long time to solve this problem.3. It is very important that all solutions (should) be checked in the original equation.4. It is suggested that this design (should) be modified at once.5. Without semiconductors, satellite communications would be impossible.6. We could also have used Theorem (6) to derive the result.7. The requirement that energy (should) be conserved must be satisfied.8. Everything here, be it a component or a device, is home-made.III、1. It was this scientist who/that discovered this phenomenon a century ago.2. Tungsten is the very metal used in electric lamps.3. The speed with which sound waves move through a medium does depend on the properties of the medium.4. It is not clear yet under what conditions it is that this formula can be used.5. This property we call inertia.IV、1. The author is engaged in the teaching of and the research on computer vision, and image processing and recognition.2. Let P and Q be two Boolean permutations of the same order, and then their composition is a new Boolean permutation.3. Three algorithms are presented, which can remarkably reduce the time to raise the pen, thus raising the drawing efficiency.4. What this paper describes is of great interest to communications engineers.5. The minimum entropy technique for estimating the Doppler frequency rate is presented, which has the advantages over the classical techniques of high accuracy and a small amount of computation.练习13II、1. By electromagnetic force is meant the potential difference across the battery when there is no flow of current.2. In the table below/which follows are listed various parameters of familiar computers.3. An element cannot be decomposed, nor can it be broken up by chemical methods.4. Only when x = 8, does this equation hold/apply.5. Of particular importance/Especially important are the two concepts which follow.6. Such a set we call the mathematical system.7. Rarely does one know this function with precision.8. This interrelationship between electric and magnetic fields makes possible such things as the electromagnet and the electric motor.9. Not until 1818 was the diffraction of light interpreted/explained.10. By no means do electrons move from the positive terminal to the negative terminal ina wire.II、1. The effect of air resistance is discussed in Chapter 15, and the decrease in acceleration with altitude in Chapter 17.2. It is necessary to determine the charge on and the voltage across this capacitor.3. In this case, no standard is needed, but only a numerical convention.4. This voltage is greater than or equal to 0.4 volt.5. The cathode, when heated, emits electrons.6. Every body, whether accelerated or not, is considered (to be) in equilibrium.7. If necessary, the wire will be covered with some insulation.8. The transistor has its materials arranged p-n-p, hence the name pnp transistor.III、1. An initial analysis is made of the performance of the device.2. The magnetic field is the space around a magnet occupied by the magnetic lines of force.3. This leads to the battery voltage in the model of 500 mV.4. This graph shows the variation with frequency of the resistance of the resistor.5. This is responsible for the direct return to the atmosphere of more than half the water that falls on the land.6. The question now arises how these unknowns can be determined.7. It is necessary to determine the effect on the device of changing the ambient temperature.8. The assumption has been made that the pressure always remains constant during the test.IV、1. The simulation results show that both the schemes are easy to implement.2. The model and algorithm proposed in this paper are to a certain degree/extent superior in performance to the conventional BP algorithm.3. A new technique for estimating the frequency deviation is proposed which gives a high accuracy and requires a small amount of computation.4. Improvement of the accuracy of range alignment in ISAR imaging (by) using the super resolution technique5. Research on and the realization of DTMF in a Cipher Coder6. Analysis of the ability of a quartz flexibility accelerometer to resist bad environment。
佩斯利英语作文
佩斯利英语作文The Paisley Pattern: A Timeless Emblem of Global InfluencePaisley, a distinctive teardrop-shaped motif, has captivated the world with its mesmerizing elegance and enduring appeal. This iconic design, rooted in the rich cultural tapestry of the East, has transcended geographical boundaries and become a universal symbol of style, creativity, and the interconnectedness of our global community.The origins of the Paisley pattern can be traced back to the ancient Persian and Indian empires where it was known as the "boteh" or "buta" design. These intricate motifs, often depicting stylized cypress trees or floral elements, were woven into the luxurious fabrics that adorned the garments of royalty and the elite. The Paisley design's symbolic significance was deeply rooted in the beliefs and traditions of these ancient civilizations, representing fertility, eternal life, and the harmonious coexistence of the physical and spiritual realms.As trade routes expanded and cultural exchange flourished, thePaisley pattern made its way westward, captivating the imagination of European textile manufacturers and fashion enthusiasts alike. In the early 19th century, the town of Paisley in Scotland emerged as a hub for the production of exquisite Paisley-patterned shawls, which became a highly coveted accessory among the aristocracy and the fashionable elite. The Paisley shawls, renowned for their intricate craftsmanship and vibrant colors, were a testament to the skilled artisanship of the Paisley weavers and the enduring allure of this timeless design.The Paisley pattern's influence extended far beyond the realm of fashion, as it began to permeate various aspects of popular culture. In the 1960s, the iconic design experienced a resurgence in popularity, becoming a hallmark of the counterculture movement and the psychedelic era. Musicians such as Jimi Hendrix and The Beatles embraced the Paisley pattern, adorning their clothing and album covers with its mesmerizing swirls and curves. This association with the vibrant and revolutionary spirit of the 1960s cemented the Paisley pattern's status as a symbol of rebellion, individuality, and the pursuit of personal expression.Today, the Paisley pattern continues to captivate designers, artists, and fashion enthusiasts worldwide. Its timeless elegance and adaptability have allowed it to transcend cultural boundaries and evolve with the changing tides of fashion and design. From high-endluxury brands to mainstream retailers, the Paisley pattern has become a ubiquitous presence, gracing everything from clothing and accessories to home furnishings and digital media.The enduring appeal of the Paisley pattern lies in its ability to evoke a sense of nostalgia, while simultaneously embodying a forward-looking, global perspective. Its intricate design and rich cultural history serve as a reminder of the interconnectedness of our world, where ideas, traditions, and artistic expressions freely cross borders and inspire new generations of creators and innovators.As we continue to navigate the complexities of our rapidly changing world, the Paisley pattern stands as a testament to the power of cultural exchange and the enduring influence of global artistic traditions. Whether adorning a high-fashion runway or a vibrant street mural, the Paisley pattern remains a symbol of the human capacity for creativity, adaptability, and the celebration of our shared cultural heritage. It is a timeless emblem that transcends the boundaries of time and space, connecting us to the rich tapestry of our collective past and inspiring us to embrace the boundless potential of our shared future.。
超越自我的英文产品宣言
超越自我的英文产品宣言Our product manifesto for "Transcendence" is a testament to our commitment to delivering a transformative experience that goes beyond the ordinary. At the heart of our manifesto lies the belief that our product is not just a commodity, but a catalyst for personal growth and self-improvement.First and foremost, "Transcendence" is built on the foundation of innovation. We strive to push the boundaries of what is possible, constantly seeking new and better ways to meet the needs and desires of our customers. Our commitment to innovation drives us to create products that not only meet current expectations but also anticipate future needs.In addition to innovation, we are dedicated to quality. Every aspect of our product, from design to functionality, is meticulously crafted to ensure the highest standard of excellence. We believe that quality is not just a feature,but a fundamental principle that underpins everything we do.Furthermore, "Transcendence" is driven by a deep understanding of our customers and their aspirations. Weaim to create a product that not only meets their needs but also inspires and empowers them to reach new heights. Our product is designed to be a companion on their journey to self-discovery and personal fulfillment.Moreover, our manifesto is rooted in the values of integrity and transparency. We are committed to beinghonest and forthright in all our dealings, ensuring thatour customers have complete trust in our product and brand. We believe that integrity is the cornerstone of a lasting and meaningful relationship with our customers.Lastly, "Transcendence" is not just a product, but a promise. It is a promise to our customers that we will continue to innovate, uphold quality, understand their needs, and operate with integrity. It is a promise to be a partner in their pursuit of transcendence, guiding and supporting them every step of the way.In conclusion, our product manifesto for "Transcendence" encapsulates our unwavering dedication to delivering a product that not only meets the needs of our customers but also elevates their lives. We are committed to pushing the boundaries of what is possible, upholding the highest standards of quality, understanding our customers' aspirations, and operating with integrity. "Transcendence" is not just a product; it is a transformative experience that inspires individuals to go beyond their limits and achieve greatness.。
担当绘就美好图的英语作文
In the realm of language,English has emerged as a global lingua franca,connecting people from diverse cultures and backgrounds.It is a language that not only facilitates communication but also serves as a canvas for expressing ideas,emotions,and aspirations.The beauty of English lies in its versatility and the richness of its vocabulary, which allows for the creation of vivid and evocative imagery.The English language is a tapestry woven with threads of history,literature,and culture. It is a language that has evolved over centuries,absorbing elements from Latin,French, German,and other languages.This rich heritage has endowed English with a vast lexicon that can be used to craft powerful narratives and express complex thoughts.One of the most striking features of English is its ability to convey emotion.The language is replete with words that can capture the subtlest of feelings.For instance,the word serene can evoke a sense of tranquility,while melancholic can express a deep sense of sadness.This emotional depth allows writers to create characters and scenarios that resonate with readers on a profound level.Moreover,English is a language that lends itself to poetic expression.Its flexible syntax and varied sentence structures enable poets to experiment with rhythm,rhyme,and imagery.From the sonnets of Shakespeare to the free verse of modern poets,English has been the medium for some of the most beautiful and moving poetry in the world.In addition to its expressive capabilities,English is also a language of precision.It is the language of science,technology,and academia,where clarity and accuracy are paramount.The ability to convey complex ideas with precision is a testament to the languages adaptability and the ingenuity of its speakers.Furthermore,English is a language that is constantly evolving.New words and phrases are continually being added to its lexicon,reflecting the changing nature of society and the world.This dynamism ensures that English remains a vibrant and relevant language, capable of adapting to the needs of its speakers.In conclusion,the English language is a beautiful and versatile tool for communication and expression.Its rich history,emotional depth,poetic potential,and capacity for precision make it a language that can be used to create vivid and compelling narratives. As the world becomes increasingly interconnected,the importance of a language like English,which can bridge cultural divides and foster understanding,will only continue to grow.。
九下英语人教版第十四单元作文
九下英语人教版第十四单元作文英文回答：In the fast-paced and ever-changing modern world, it is essential for individuals to possess a strong sense of adaptability in order to navigate its complexities and challenges effectively. Adaptability, defined as theability to adjust or change oneself in response to new or different circumstances, is a crucial skill that empowers us to embrace new experiences, learn from our mistakes, and grow as individuals. It plays a pivotal role in our personal, academic, and professional lives, enabling us to thrive in diverse environments and achieve our full potential.One of the key benefits of adaptability is its transformative impact on our learning and development. In an educational setting, students who exhibit adaptability are better equipped to handle the rigors of academic coursework, embrace new learning styles, and seek outopportunities for personal growth. They are open to constructive criticism, view challenges as learning opportunities, and are not afraid to step outside of their comfort zones. By embracing adaptability, students can maximize their academic potential, cultivate a lifelong love for learning, and prepare themselves for future success in higher education and beyond.In the professional realm, adaptability is a highly sought-after quality. Employers value individuals who can adapt quickly to changing market conditions, technological advancements, and evolving industry trends. Adaptable employees are able to learn new skills on the go, adjust to new responsibilities, and work effectively in diverse team environments. They are proactive in seeking out opportunities for professional development, recognize the importance of continuous learning, and are willing to take calculated risks to advance their careers. By demonstrating adaptability in the workplace, individuals can increase their job satisfaction, enhance their earning potential, and establish themselves as valuable assets to their organizations.Moreover, adaptability plays a crucial role in our personal lives. It enables us to navigate the complexities of human relationships, manage stress effectively, and cope with unexpected life events. Individuals who are adaptable are better able to adjust to changes in their personal circumstances, such as moving to a new city, starting a new job, or facing financial challenges. They are resilient in the face of adversity, possess a positive outlook on life, and are able to maintain a healthy work-life balance. By embracing adaptability in our personal lives, we can cultivate a sense of inner peace, build stronger relationships, and live more fulfilling and meaningful lives.In conclusion, adaptability is an essential skill that empowers us to thrive in the modern world. By embracing adaptability in all aspects of our lives, we can unlock our full potential, maximize our learning opportunities, achieve professional success, and navigate the complexities of human relationships. It is a quality that should be nurtured and cultivated from a young age, as it providesthe foundation for personal growth, lifelong success, and a fulfilling life.中文回答：在瞬息万变的现代世界中，个人必须具备很强的适应能力，才能有效应对它的复杂性和挑战。
完美匹配层边界条件
完美匹配层边界条件1.引言1.1 概述概述部分是对整篇文章的简要介绍，旨在引起读者的兴趣并提供必要的背景信息。
在这一部分，我将描述完美匹配层边界条件的概念和重要性。
完美匹配层边界条件是在计算机科学和计算机工程领域中使用的概念。
它是指在计算机系统或网络中，两个相邻层之间的接口需要相互兼容和协同工作，以实现高效的数据传输和功能交互。
在计算机网络中，每个层都有其特定的功能和责任，例如数据链路层、网络层、传输层等。
这些层之间的交互和数据传输需要满足一定的条件和协议，以确保数据的正确性和可靠性。
完美匹配层边界条件正是为了保证这种交互的顺利进行而提出的要求。
完美匹配层边界条件的重要性在于它能够确保系统的稳定性和效率。
如果层之间的边界条件不匹配或没有被正确处理，可能会导致数据传输错误、性能下降甚至系统崩溃。
因此，了解和正确处理完美匹配层边界条件对于构建可靠和高效的计算机系统和网络至关重要。
在接下来的正文部分，我将详细介绍完美匹配层边界条件的具体要点和实现方法。
并提供一些实际应用场景和案例研究，以便读者更好地理解和应用这一概念。
综上所述，完美匹配层边界条件是保证计算机系统和网络正常运行所必需的关键要素。
只有通过正确理解和应用这些条件，我们才能构建出稳定、高效和可靠的计算机系统和网络。
接下来的文章将进一步探讨这一主题，并提供更多有关完美匹配层边界条件的深入内容和实践经验。
1.2 文章结构文章结构部分是在引言部分之后，正文部分之前的一个小节，主要是对整篇文章的结构进行介绍和概述。
在这部分内容中，我们可以重点介绍一下文章的大致结构和各个部分的内容安排。
具体可以按照以下内容编写：在本文中，我们将详细讨论完美匹配层边界条件。
本文分为引言、正文和结论三个部分。
在引言部分（第1部分）中，我们将首先对完美匹配层进行概述，介绍其基本概念和背景。
接着，我们将描述本文的结构，即正文和结论的内容安排。
最后，我们将明确本文的目的，即通过研究和分析完美匹配层边界条件的相关问题，提出一些有益的观点和结论。
持久见真金的英语作文
Endurance is a quality that can reveal the true character of a person,much like gold that remains pure and valuable over time.It is a trait that is often tested in various aspects of life,from personal challenges to professional endeavors.In the realm of personal growth,endurance is the ability to persist through difficult times without giving up.It is the strength to carry on when the odds are against you,and the resilience to bounce back from setbacks.This quality is particularly important in the face of adversity,as it allows individuals to maintain their composure and continue striving for their goals.In the professional sphere,endurance is equally crucial.It is the capacity to work tirelessly towards a project or a career goal,even when faced with obstacles or delays.It is the determination to see a task through to completion,regardless of the time and effort it requires.This trait is highly valued in the workplace,as it demonstrates commitment, reliability,and a strong work ethic.Moreover,endurance is not just about physical stamina it also encompasses mental and emotional fortitude.It is the ability to stay focused and motivated,even when faced with challenges that test ones patience and resolve.This mental resilience is essential for maintaining a positive attitude and overcoming the inevitable hurdles that life presents.In sports,endurance is a key factor in achieving success.Athletes who possess this quality are able to push their bodies to the limit,enduring rigorous training and competition to reach their peak performance.They are able to outlast their opponents, demonstrating their superior stamina and willpower.In relationships,endurance is the foundation of a strong and lasting bond.It is the ability to weather the storms of life together,to support each other through thick and thin.It is the commitment to stand by ones partner,even in the face of adversity,and to work together to overcome challenges.In conclusion,endurance is a vital quality that can reveal the true mettle of an individual. It is a testament to ones strength,resilience,and determination,and it is a trait that is highly valued in all aspects of life.By cultivating endurance,we can rise to the challenges that come our way and emerge as stronger,more capable individuals.。
基于UPML的三维FDTD正演模拟
基于UPML的三维FDTD正演模拟胡灵娟;唐新功;潘秋瑾;邵佳园;孙游雪【期刊名称】《中州煤炭》【年(卷),期】2018(040)004【摘要】采用时域有限差分法(Finite-Difference Time Domain,FDTD)计算电磁场问题时需要设置适当的吸收边界条件(Absorbing Boundary Condition,ABC),从而将无限空间转化为有限空间来模拟电磁波的传播情况及其规律.讨论了单轴各向异性完全匹配层(Uniaxial Perfectly Matched Layer,UPML)吸收边界条件下的三维时域有限差分法,介绍了一般FDTD的基本原理,推导了基于UPML的三维FDTD的迭代公式,采用FDTD-UPML对电磁波在三维空间的传播情况进行正演模拟.数值模拟结果表明,结合具有强大图形处理功能的Matlab编程软件,使得FDTD-UPML能够很直观地模拟电磁波在三维空间中的传播情况.【总页数】4页(P138-141)【作者】胡灵娟;唐新功;潘秋瑾;邵佳园;孙游雪【作者单位】长江大学油气资源与勘探技术教育部重点实验室,湖北武汉 430100;长江大学地球物理与石油资源学院,湖北武汉 430100;长江大学地球物理与石油资源学院,湖北武汉 430100;湖北师范大学数学与统计学院,湖北黄石 435002;长江大学地球物理与石油资源学院,湖北武汉 430100;长江大学地球物理与石油资源学院,湖北武汉 430100【正文语种】中文【中图分类】O441.4【相关文献】1.基于FDTD的探地雷达道路检测正演模拟 [J], 许德根;杨天春;张启;焦春春;唐志成2.基于单轴各向异性完全匹配层边界条件的ADI-FDTD三维GPR全波场正演 [J], 冯德山;谢源3.基于FDTD的隧道衬砌质量雷达检测正演模拟及其应用分析 [J], 张杨;肖国强;周黎明;余信江4.基于UPML的三维FDTD正演模拟 [J], 胡灵娟;唐新功;潘秋瑾;邵佳园;孙游雪;;;;;;5.基于FDTD的探地雷达正演模拟分析 [J], 吕宁宁因版权原因，仅展示原文概要，查看原文内容请购买。
羽毛球英语作文高二
Badminton is a sport that has gained immense popularity across the globe, and it is particularly favored among high school students. As a sport, badminton offers a unique blend of speed, agility, and strategy, making it an ideal choice for those looking to improve their physical fitness and mental acuity.In high school, students are often encouraged to participate in various extracurricular activities, and badminton is one such activity that can provide numerous benefits. Firstly, badminton is a great way to stay physically active. It requires players to move quickly and make sudden changes in direction, which helps to improve cardiovascular health and overall stamina.Secondly, badminton is a sport that demands mental focus and strategic thinking. Players must anticipate their opponents moves and devise a plan to counter them effectively. This not only helps to sharpen ones reflexes but also enhances problemsolving skills and decisionmaking abilities.Moreover, badminton is a social sport that fosters camaraderie and teamwork. Playing badminton with friends or joining a school team can help students develop strong interpersonal relationships and learn the importance of cooperation and communication.In addition to these benefits, badminton can also be a fun and enjoyable pastime. The fastpaced nature of the game, combined with the thrill of scoring points and winning matches, can provide a sense of accomplishment and satisfaction.However, it is important for high school students to maintain a balance between their academic responsibilities and extracurricular activities. While badminton can be a rewarding and enriching experience, it should not come at the expense of ones studies or other important commitments.In conclusion, badminton is a fantastic sport for high school students to engage in. It offers a multitude of benefits, including physical fitness, mental stimulation, and social interaction. By participating in badminton, students can enhance their wellbeing and develop valuable life skills that will serve them well in the future.。
二维DGTD方法中UPML吸收边界的实现
二维DGTD方法中UPML吸收边界的实现李林茜;魏兵;杨谦;葛德彪【摘要】针对二维情形单轴各向异性完全匹配层吸收边界条件,研究了横磁波情形时域离散伽略金算法单轴各向异性完全匹配层吸收边界的理论基础和实现方案.借鉴时域有限差分方法——时域离散伽略金算法中吸收边界阻抗匹配、各向异性介质参数设置和匹配矩阵等思想,结合时域离散伽略金算法空间离散网格的非结构特性和离散单元之间场量传递的特点,给出了在单轴各向异性完全匹配层中电磁场量时域迭代公式,进一步离散成为离散时域迭代计算式.由于时域离散伽略金算法网格的非结构特性,一阶SM吸收边界条件一般对入射电磁波的反射率在-24 dB左右.仿真算例说明,给出的时域离散伽略金算法单轴各向异性完全匹配层吸收边界对电磁波的双重衰减达130dB,表明单轴各向异性完全匹配层具有良好的吸收效果.【期刊名称】《西安电子科技大学学报（自然科学版）》【年(卷),期】2016(043)006【总页数】5页(P86-90)【关键词】时域离散伽略金方法;单轴各向异性完全匹配层;横磁波【作者】李林茜;魏兵;杨谦;葛德彪【作者单位】西安电子科技大学物理与光电工程学院,陕西西安710071;西安电子科技大学信息感知协同创新中心,陕西西安710071;西安电子科技大学物理与光电工程学院,陕西西安710071;西安电子科技大学信息感知协同创新中心,陕西西安710071;西安电子科技大学物理与光电工程学院,陕西西安710071;西安电子科技大学信息感知协同创新中心,陕西西安710071;西安电子科技大学物理与光电工程学院,陕西西安710071;西安电子科技大学信息感知协同创新中心,陕西西安710071【正文语种】中文【中图分类】O441.4截断边界条件是许多电磁场数值方法精度保证的关键．在过去几十年，学着们提出许多种吸收边界条件，并成功应用于时域有限差分(Finite Difference Time Domain， FDTD)等方法中[1-2] ．文献[3]中提出了完全匹配层(Perfectly Matched Layer， PML)吸收边界，该边界是在计算域最外面增加一层非物理吸收层，该吸收层与相邻区域阻抗匹配，进入PML层的电磁波因为层内介质参数渐变而迅速衰减．后来有人提出的坐标伸缩完全匹配层(Coordinate stretched Perfectly Matched Layer， CPML)以及各向异性完全匹配层(Uniaxial anisotropy Perfectly Matched Layer， UPML)，均具有良好效果．时域离散伽略金(Discontinuous Galerkin Time Domain， DGTD)方法[4-5] 是基于时域体积元发展起来的一种兼备时域有限元(Finite Element Time Domian，FETD)方法网格剖分的灵活性和FDTD显式迭代特点的算法．文献[6]中将PML技术应用于DGTD，其后，文献[7]将PML技术应用于共形的三维DGTD计算．文献[8]提出一种DGTD提高PML稳定性的方案．文献[9-10]中讨论了高阶结点DGTD方法中的PML问题．上述文献主要讨论三维问题，然而在很多的情形，例如金属搭接缝中的电波传播问题、层状介质中的波传播问题、地面上方长传输线的电磁场分布、地下长线缆的电磁场分布问题和光纤里的光传输问题等都可以简化成二维问题来处理．考虑到二维方案在解决许多问题中方便快捷的特性，系统地研究DGTD算法的二维UPML吸收边界具有重要的意义．文中从各向异性介质中的Maxwell方程组和UPML基本理论出发，得到UPML介质层中的支配方程和辅助方程．考虑到DGTD空间离散网格的非结构特性，结合离散单元之间场量传递的特点，将方程加权积分得到单元矩阵方程．进一步，考虑相邻单元之间电磁场矢量切向分量突变的通量边界条件，通过基函数展开和矩阵单元计算，得到具有通量形式的时域公式，进而得到横磁(Transverse Magnetic，TM)波情形UPML中的时域迭代计算式．数值结果说明，文中UPML吸收边界对电磁波的衰减达 130 dB，吸收效果良好，满足二维情形电磁场精确仿真的需求．UPML是指在计算域外部增加一层非物理区域，该区域中为各向异性介质．实际操作中适当选择各向异性介质的本构参数，PML层波阻抗与相邻区域匹配，使入射到分界面上的电磁波无反射地进入该区域．在PML层中，电场和磁场满足的含辅助变量的支配方程为[11]其中，μ1和ε1为主要计算域中的介电系数和磁导率；a、b和c均为对角张量(具体表示为 a= diag(axx，ayy，azz)，其余类似)；辅助变量Ph和Pe与电场E和磁场H之间满足的微分方程为其中，d和κ同样为对角阵．UPML实现过程中，需要获得式(1)和式(2)的分量式并离散．对于TM波，关注的电磁场分量为Ez、Hx和Hy．因此，式(1)可转化为其中，辅助函数Ph和Pe的分量式为将式(4)代入式(3)，得TM波情形支配方程式(1)所满足的分量方程，即方程式(2)的分量式为分量方程式(5)和式(6)在具体实现数值计算时，需要改写为离散的时域递推公式．离散方案依赖于空间离散单元和基函数的选取等．在FDTD方法中常采用六面体离散计算域，并采用点匹配法，而DGTD与FETD类似常采用三维四面体或二维三角形离散单元和伽辽金法．由于采用非结构性网格离散，DGTD的UPML实现更为复杂．UPML区域划分如图1所示．在包含目标的计算域外部，吸收边界被划分成为4个棱边区和4个平面区．不同于FETD中单元交界面处采用电磁场连续的强制边界条件，DGTD采用数值通量的方式实现网格之间的场量交互．TM波情形在边界上交互时数值通量定义为[5]其中，m和m+分别表示当前元和相邻单元；和为通量系数；nx和ny分别表示单元中棱边的外法向单位矢量在x和y方向的投影．在式(7)通量定义的基础上，通过加权积分[12]和基函数展开，可得分量方程式(5)对应的矩阵方程，即其中，上标m为单元编号; Mm为单元质量矩阵；Sx和Sy为刚性矩阵；Fe，z、Fh，x和Fh，y分别指电场e和磁场h的通量变化量函数．将式(8)和式(9)在t=nΔt处离散，式(10)在t=(n+1/2) Δt处离散，可得其中，αgx、βgx、αgy、βgy、αgz和βgz为常系数．辅助方程式(6)无需加权积分，直接离散可得其中，ch、ci、cj和ck为常系数．式(11)～(16)就是二维TM波情形DGTD算法中UPML区域的递推计算公式．设二维计算域为8 m×8 m的矩形，区域离散为 10 902 个结点，共 21 474 个三角形单元，UPML层厚为 1 m．线源在计算域中心处．UPML层中电导率σ为非均匀分布，其渐变公式为其中，d为UPML区中单元的重心坐标位置；d0为UPML内侧界面位置；Δd为UPML层厚度；m为整数，本算例中 m=4．计算时，时间离散间隔Δt=0.16×10-10 s，当辐射电磁波的频率 f=0.3 GHz 时，文中方法的计算结果与利用Hankel函数得到的解析解的比较如图2所示．图2中三角形和实线分别表示文中算法和解析解的结果，由图可见，两种算法的计算结果一致，这说明了文中吸收边界算法的有效性．为更好地说明电磁波进入UPML层内的衰减情况，下面给出在辐射线源和计算域最外端连线上场值的分布情形．图3(a)是线元辐射的场值快照，线源位于A点处．线段AB上的电场如图3(b)所示，由图可见，电磁波在刚进入UPML层的阶段衰减不大(这是由于界面附近参数接近于内部计算域，便于电磁波无反射地进入吸收层)．随着电磁波深入UPML层，衰减量逐步加大(吸收层参数设置渐变所致)．吸收层界面上场值约为 -25 dB，而到吸收层外侧已下降到 -90 dB 以下．场值衰减为入射场的 1/500，考虑到返回计算域的电场值还需经过相同的路径，这一衰减的效果将加倍．文中从二维UPML的基本理论出发，根据空间离散网格的非结构特性，结合DGTD中离散单元之间场量传递的特点，在TM波情形下推导了DGTD各向异性完全匹配层吸收边界中的迭代计算式，实现了波在UPML层中的衰减．仿真算例说明，文中给出的DGTD UPML吸收边界对电磁波的双重衰减达 130 dB，吸收效果良好，满足二维情形电磁场精确仿真的需求．【相关文献】[1] 王林年, 褚庆昕, 梁昌洪. 交替方向隐式时域有限差分法中的Berenger理想匹配层[J]. 西安电子科技大学学报, 2006, 33(3): 458-461.WANG Linnian, CHU Qing xin, LIANG Changhong. Berenger’s Perfectly Matched Layer for the Alternating Direction Implicit Finite-difference Time-domain Method[J]. Journal of Xidian University, 2006, 33(3): 458-461.[2]姜彦南,葛德彪,杨利霞.卫星模型散射FDTD计算的共形边界研究[J]. 西安电子科技大学学报, 2007, 34(4): 587-589.JIANG Yannan, GE Debiao, YANG Lixia. Conformal Boundary Scheme in FDTD Computation of Satellite Model Scattering[J]. Journal of Xidian University, 2007, 34(4): 587-589.[3]BERENGER J P. A Perfectly Matched Layer for the Absorption of ElectromagneticWaves[J]. Journal of Computational Physics, 1994, 114(2): 185-200.[4]CHEN J, LIU Q H. Discontinuous Galerkin Time-domain Methods for Multiscale Electromagnetic Simulations: a Review[J]. Proceedings of the IEEE, 2013, 101(2): 242-254.[5]ALVAREZ J. A Discontinuous Galerkinfinite Element Method for the Time-domain Solution of Maxwell Equations[D]. Granada: University of Granada, 2013: 31-39.[6]XIAO T, LIU Q H. Three-dimensional Unstructured-grid Discontinuous Galerkin Method for Maxwell’s Equations with Wel l-posed Perfectly Matched Layer[J]. Microwave and Optical Technology Letters, 2005, 46(5): 459-463.[7]STYLIANOS D, LEE J F. Interior Penalty Discontinuous Galerkin Finite ElementMethod for the Time-dependent First Order Maxwell’s Equations[J]. IEEE Transa ctions on Antennas and Propagation, 2010, 58(12): 4085-4090.[8]PENG D, CHEN L, YIN W L, et al. An Efficient DGTD Implementation of the Uniaxial Perfectly Matched Layer[C]//Proceedings of the 2013 International Symposium on Antennas & Propagation: 2. Piscataway: IEEE, 2013: 1272-1275.[9]JI X, CAI W, ZHANG P. Reflection/Transmission Characteristics of a Discontinuous Galerkin Method for Maxwell’s Equations in Dispersive Inhomogeneous Media[J]. Journal of Computational Mathematics-international Edition, 2008, 26(3): 347-364. [10]NIEGEMANN J, KÖNIG M, STANNIGEL K, et al. Higher-order Time-domain Methods for the Analysis of Nano-photonic Systems [J]. Photonics and Nanostructures-Fundamentals and Applications, 2009, 7(1): 2-11.[11]GEDNEY S D, KRAMER T, LUO C, et al. The Discontinuous Galerkin Finite Element Time Domain Method (DGFETD)[C]//IEEE International Symposium on Electromagnetic Compatibility. Piscataway: IEEE, 2008: 1-4.[12]JIN J M. The Finite Element Method in Electromagnetics [M]. 3rd Edition. New York: John Wiley &Sons, 2014: 37.。
UPML媒质中的包络ADI-FDTD
UPML媒质中的包络ADI-FDTD
倪海婷;吴萍
【期刊名称】《太赫兹科学与电子信息学报》
【年(卷),期】2007(005)005
【摘要】由于交替方向隐式时域有限差分法(Alternating-Direction Implicit Finite-Difference Time Domain,ADI-FDTD)的数值色散会随着时间步长的增加而增加,文中讨论了单轴各向异性完全匹配层(uniaxial perfectly matched layer,UPML)媒质中包络交替方向隐式时域有限差分法(Envelope ADI-FDTD),推导了二维Envelope ADI-FDTD UPML的迭代公式,并提出一种新的离散方法.与ADI-FDTD UPML相比,改进后的Envelope ADI-FDTD UPML的时间步长可以取得更大,且能有效地修正相速误差,从而减少数值色散,提高计算精度.
【总页数】5页(P364-368)
【作者】倪海婷;吴萍
【作者单位】安徽大学,电子科学与技术学院,安徽,合肥,230039;安徽大学,电子科学与技术学院,安徽,合肥,230039
【正文语种】中文
【中图分类】TN011
【相关文献】
1.UPML媒质中无条件稳定的二维ADI-FDTD方法 [J], 赵延文;聂在平
2.色散媒质中ADI-FDTD的PML [J], 王禹;袁乃昌
3.周期结构三维ADI-FDTD算法的UPML边界条件 [J], 黄刘宏;毛云飞;丁世敬;李跃波
4.混合ADI-FDTD亚网格技术在探地雷达频散媒质中的高效正演 [J], 冯德山;陈佳维;吴奇
5.色散媒质中采用Z变换的ADI-FDTD方法 [J], 徐利军;王禹;袁乃昌
因版权原因，仅展示原文概要，查看原文内容请购买。
修正的卷积完全匹配层技术
修正的卷积完全匹配层技术谢国大;宋开宏;黄志祥【摘要】The numerical computation time is not consistent between the complex frequency-shifted convolutional perfectly matched layer(CPML) and the recursive formula of the finite-difference time-domain(FDTD) method .It is found that the absorption effect of CPML does not reach the absorption effect of some perfectly matched layers(PMLs) with the same second-order accuracy in many numeri-cal examples .In this paper ,the time average approximation method is applied to modifying the tradi-tional CPML ,making sure that its absorption effect nearly has the same performance with other PMLs which have the same numericalaccuracy .The validity of this method is verified by two repre-sentative examples .T he presented method based on the simple modification to the traditional CPM L code can greatly reduce the computation time ,w hich is of significance for the efficient application of CPML in the FDTD algorithm .%复频移的卷积完全匹配层(convolutional perfectly matched layer,CPM L)与时域有限差分(finite-difference time-domain,FDTD)算法递推公式之间存在数值计算时间不同步的问题,诸多算例结果表明CPML的吸波效果并没有达到一些具有相同二阶精度的完全匹配层(perfectly matched layer,PML)的吸波效果.文章采用时间平均近似方法对CPML进行了修正,使其吸波性能与其他具有相同数值计算精度的PML的吸波性能相当;通过2个具有代表性的算例,验证了方法的有效性.该方法思路简单、清晰,只需在传统的CPML代码基础上进行简单的修改,计算时间大大缩减,该方法对于CPML在FDTD算法中的高效应用具有一定的意义.【期刊名称】《合肥工业大学学报（自然科学版）》【年(卷),期】2017(040)012【总页数】4页(P1725-1728)【关键词】时域有限差分(FDTD)算法;卷积完全匹配层(CPML);吸收效果;时间平均近似方法;计算时间【作者】谢国大;宋开宏;黄志祥【作者单位】安徽大学电子信息工程学院,安徽合肥 230039;安徽大学电子信息工程学院,安徽合肥 230039;安徽大学电子信息工程学院,安徽合肥 230039【正文语种】中文【中图分类】O441.4自从Berenger于1994年提出完全匹配层(perfectly matched layer,PML)[1]吸收边界条件以后,PML已经成为有效的吸收边界条件技术,随后一些其他形式的PML也相继被提出来,例如,各向异性完全匹配层(uniaxial perfectly matched layer,UPML)[2]、坐标伸缩完全匹配层(stretched-coordinate perfectly matched layer,SC-PML)[3]等。
在火星上怎么呼吸英语作文
Breathing on Mars presents a unique set of challenges due to the stark differences in the Martian atmosphere compared to Earths. If you were to find yourself on the red planet, heres how you could approach the issue of respiration:1. Atmospheric Composition: Mars atmosphere is composed of about 95% carbon dioxide, with traces of nitrogen and argon, and extremely low levels of oxygen. Humans cannot breathe this directly, as it lacks the necessary oxygen to support human life.2. Pressure and Temperature: The atmospheric pressure on Mars is only about 0.6% of Earths, which is too thin to allow for the efficient exchange of gases in the lungs. Additionally, the average temperature on Mars is around 80 degrees Fahrenheit 60 degrees Celsius, which would make it inhospitable for human survival without proper protection.3. Use of Life Support Systems: To breathe on Mars, you would need a life support system that provides a breathable atmosphere. This could include a spacesuit with an oxygen supply or a habitat module with an artificial atmosphere.4. Oxygen Generation: One potential solution for longterm habitation is the use of technology to generate oxygen from the Martian atmosphere. The Mars 2020 missions MOXIE Mars Oxygen InSitu Resource Utilization Experiment is an example of such technology, which aims to convert carbon dioxide into oxygen.5. Habitat Design: A pressurized habitat would be essential for creating a breathable environment. This habitat would need to be designed to maintain a stable pressure and temperature, as well as provide a continuous supply of oxygen.6. Physical Adaptations: While not a practical solution for immediate survival, in the long term, genetic adaptations or enhancements could potentially allow humans to tolerate the Martian atmosphere to some extent. However, this is purely speculative and currently beyond our scientific capabilities.7. Emergency Breathing Apparatus: In case of an emergency, such as a spacesuit malfunction, a portable oxygen supply or an emergency breathing apparatus would be crucial for survival until a safe environment can be reached.8. Research and Development: Continued research into the Martian environment and human physiology is necessary to develop effective solutions for breathing on Mars. This includes understanding the longterm effects of the Martian atmosphere on the human body.In conclusion, breathing on Mars is not possible under natural conditions due to the lack of oxygen and the inhospitable atmospheric pressure and temperature. The use of advanced technology and life support systems is essential for any human presence on the planet. As our understanding of Mars and our technological capabilities advance, so too will our ability to overcome these challenges.。