The Processing of Temporal Intervals Reflected by CNV-Like Brain Potentials
英语入门600词汇
英语入门600词汇English Answer:Introduction.Diving into the captivating realm of language acquisition, English, specifically, presents a treasure trove of opportunities for communication and knowledge exploration. As you embark on this enriching journey, mastering a foundational vocabulary will serve as a stepping stone, unlocking the gateway to fluency and comprehension. This article will meticulously guide you through a curated list of 600 essential English words, meticulously chosen to empower you with the linguistic building blocks for effective communication.The Power of 600。
Why 600 words? Research has consistently demonstrated that a vocabulary of this size enables non-native speakersto comprehend up to 90% of everyday English conversations and written texts. By internalizing these fundamental words, you will gain the confidence to engage in meaningful interactions, express your thoughts and ideas with precision, and navigate the intricacies of English grammar.The Foundation: Essential Vocabulary Categories.Our curated list encompasses a comprehensive range of vocabulary categories, meticulously selected to provide a well-rounded foundation for your English language proficiency. These categories include:Nouns: The building blocks of language, nounsrepresent people, places, things, and concepts. Fromtangible objects like "book" and "car" to abstract ideaslike "happiness" and "knowledge," nouns form the core ofour vocabulary.Verbs: The workhorses of language, verbs describe actions, states, and occurrences. Whether it's "run," "sing," "think," or "exist," verbs bring dynamism andmeaning to our words.Adjectives: The colorful brushstrokes of language, adjectives add depth and detail to our descriptions. From "big" and "small" to "interesting" and "beautiful," adjectives paint a vivid picture of the world around us.Adverbs: The modifiers of modifiers, adverbs fine-tune the meaning of verbs, adjectives, and even other adverbs. By adding precision to our speech, adverbs enhance our ability to express ourselves effectively.Determiners: The gatekeepers of nouns, determiners specify the quantity or identity of the noun they precede. Whether it's "the," "a," "some," or "any," determiners provide crucial information about the noun's role in the sentence.Pronouns: The stand-ins for nouns, pronouns replace nouns to avoid repetition and ensure smooth sentence flow. From "I" and "you" to "he," "she," and "they," pronouns streamline our communication.Prepositions: The spatial and temporal connectors, prepositions establish relationships between words in a sentence. Think "in," "on," "at," "by," and "to." Prepositions add depth and context to our speech.Conjunctions: The sentence builders, conjunctions connect words, phrases, and clauses. Whether it's "and," "but," "or," or "because," conjunctions create logical flow and coherence in our writing and speech.Tips for Mastering Your Vocabulary.Embarking on this vocabulary-building journey requires dedication and a strategic approach. Here are some proven tips to help you achieve optimal results:Immerse Yourself: Surround yourself with English through reading, listening, and engaging in conversations. The more you expose yourself to the language, the faster your vocabulary will grow.Use Spaced Repetition: Review your vocabularyregularly using spaced repetition techniques. This involves reviewing words at increasing intervals, which helps strengthen your memory and recall.Engage with Word Roots and Etymology: Comprehending the roots and origins of words can unlock their deeper meanings and facilitate memorization.Utilize Flashcards and Word Lists: Create flashcards or utilize online word lists to practice and test your vocabulary regularly.Seek Feedback and Practice Conversation: Engage in conversations with native speakers or language partners to practice your vocabulary and receive feedback on your pronunciation and usage.Conclusion.The journey to fluency and comprehension in English begins with a solid vocabulary foundation. By masteringthese 600 essential words, you will unlock the ability to communicate effectively, understand diverse texts, and express yourself with clarity and precision. Embrace the learning process, utilize the provided tips, and embark on this linguistic adventure with enthusiasm. With dedication and perseverance, you will transform your Englishvocabulary into a powerful tool for personal growth and global communication.Chinese Answer:引言。
急性岛叶梗死综合征临床研究
Acute Insular Infarct Syndrome : 20 Cases Report W U X i ao2w ei , L IU X i n g2z hou , H UA N G Guan g , et al . De p art ment of N eurol2 og y , Fu x i n g Hos pit al of Ca pit al Me dical U ni versit y , B ei j i n g 100038 , Chi na
17 例患者于入院后急性期内行 Holter 监测 ,依患者是否 发生心房纤颤分别分析 。无心房纤颤的患者共 12 例 ,多为左 侧梗死 (9 例) ,以室上性早搏为主 ,其中发作成对的室上性早搏 者 4 例 ,1 例出现了短阵房性心动过速 ,不完全性右束支传导阻 滞 (均为左侧梗死) ;发生频发室性早搏 1 例 (右侧梗死) ,有时 呈间位性 。根据《中华心血管病杂志》编委会心率变异性对策
岛叶位于外侧裂深部 ,由岛盖覆盖 。目前 ,人们对岛叶的 功能尚未全面认识 。在脑血管病中 ,单独岛叶梗死很罕见 ,岛 叶梗死通常合并其他外侧裂周围脑组织 (如颞叶 、额叶 、顶叶) 的缺血坏死 。我们将具有岛叶梗死的一组症状称为岛叶梗死 综合征 。现将我院 2005 年 1 月～2008 年 9 月住院的岛叶梗死 综合征 20 例报道如下 。 1 对象与方法 1. 1 对象 选取 2005 年 1 月～2008 年 9 月住院的岛叶梗死综 合征确诊患者 20 例 ,均为初次发生的累及一侧岛叶的缺血性 脑梗死 。排除标准 : ①大脑中动脉 M1 段急性闭塞导致的大面 积脑梗死 ; ②出血性脑梗死 。岛叶梗死对心血管系统影响的入
TEMPORALADVERBIA...
Temporal Adverbials, Negation, and the Bangla PerfectWe establish that the perfect in Bangla has an unusual restriction: it does not allow adverbs to modify the reference time. We propose a syntactic account and we further suggest that another puzzling fact about the perfect in Bangla – that it cannot be negated (Ramchand 2005) – stems from the prohibition against reference time modification.Adverbial Modification. The past perfect in several languages is ambiguous when modified by so-called ‘positional’ temporal adverbials, i.e., adverbials that make reference to specific time intervals (e.g., McCoard 1978, Giorgi and Pianesi 1998, Musan 2001). In (1) the adverbial can restrict either the time interval at which the event holds – the event time (ET), or the time interval from the perspective of which the event is described – the reference time (RT), (ignoring the issue of how the two readings correlate with word order). Similar ambiguities obtain with the present perfect, see (2). In contrast, the Bangla perfect does not allow RT modification: (3) and (4) only have an ET modification reading – the submission happened on Sunday/today.(1) (On Sunday) Rick had submitted the homework (on Sunday). √ET√RT(2) (Today) Rick has submitted the homework (today). √ET√RT(3) robibare rik homwark jOma kor-e-ch-il-o √ET * RTSunday-loc Rick homework submission do-e-ch-past-3‘Rick had submitted the homework on Sunday.’(4) aj(-ke) rik homwark jOma kor-e-ch-e √ET* RTtoday Rick homework submission do-e-ch-3‘Rick has submitted the homework today.’The -e-ch forms are perfects.Could the -e-ch forms in Bangla, as in (3) and (4), be simple tenses rather than perfects, thus accounting for the absence of ambiguity of adverbial modification? Several facts reveal that this is not so: (i) the present perfect allows modification by now, while the past progressive and the simple past do not, suggesting that the present perfect is not simply another past tense form (see (5)); (ii)in embedded clauses, the present perfect requires the ET to precede a past RT introduced by the matrix tense, as in (6) and (7), suggesting that it does not behave as a present tense (it could still, of course, be like a simple past, in a language without sequence of tense); (iii) person marking varies with tense; the present perfect inflects as a present tense and the past perfect inflects as a past tense (cf. the 3 person kor-e-ch-e ‘has done’, kor-ch-e‘is doing’, kOr-e‘does’; vs. kor-e-ch-il-o ‘had done’, kor-ch-il-o ‘was doing’, kor-l-o‘did’). Finally, the -e-ch forms are considered perfects in Chatterji (1926), Chattopadhyay (1988), and Ramchand (2004). Thus, the puzzle of adverbial modification is real.(5) ekhon rik homwark jOma { kor-e-ch-e / * kor-ch-il-o / * kor-l-o }now Rick homework submission do-e-ch-3 do-ch-past-3 do-past-3‘Rick {has submitted / * was submitting / *submitted} the homework now’(6) ami baRi eS-e jan-l-am je Se eS-e-ch-il-oI home come-e know-past-1 that he come-e-ch-past-3‘Having come home, I knew that he had come.’ (Chattopadhyay 1988: 22)(7) ami bol-l-am o LA-te thek-e-ch-eI say-past-1 he LA-loc stay-e-ch-3‘I said he lived in LA.’ (only precedence, no simultaneous reading)1Analysis. The affix -ch, a remnant of the auxiliary verb ach- ‘be’ (Lahiri 2000, Butt and Lahiri 2002) spells out a semantically vacuous functional item that embeds PERFECT(and also IMPERFECTIVE, as in kor-ch-il-o ‘was doing’, but we put this aside). See (8) for a hierarchical representation (ignoring word order).(8) [T ENSE[-ch[PERFECT[VIEWPOINT ASPECT[v P ]]]]]The lexical semantics of PERFECT is as in (9), which follows Pancheva and von Stechow (2004) in treating the PERFECT as a weak relative past: it introduces an interval no part of which may follow the reference time introduced by TENSE.(9) [[PERFECT]] = λp<i,t> λt i ∃t′i [t′≤ t & p(t′)] (t′≤ t iff there is no t″⊂ t′, s.t. t″ > t)The affix -e, both on its own, e.g., baRi eS-e ‘having come’ in (6), and in combination with -ch in the perfect, marks RESULTATIVE viewpoint; see (10) for its semantics. The composition of PERFECT and RESULTATIVE yields the needed semantics for Bangla perfects, which lack universal readings (see also Ramchand 2005).(10) [[RESULTATIVE]]= λP<v,t> λt i∃s∃e [t ⊂τ(s) & s is a target state of e & P(e)]The PERFECT moves to the affix –ch and then to T ENSE; this syntax precludes adverbs from being merged and interpreted higher than PERFECT. Accordingly, the LF in (11a) is not possible; only the one in (11b) is. (11a) derives RT modification (see (12a), and it is not available in the Bangla perfect. (11b) is the LF behind ET modification (see (12b), and it is the only structure available in the Bangla perfect. Thus, we account for the restriction on temporal modification in (3)-(4).(11) a.*[T ENSE - ch [adverbial[PERFECT[RESULTATIVE →-e [v P ]]]]]]b. [T ENSE-ch -PERFECT[adverbial[RESULTATIVE →-e [v P ]]]]]](12) a. * ∃t [t < t c & t ⊆Sunday & ∃t′ [t′≤ t & ∃s∃e [t′⊂τ(s) & s is a target state of e & P(e)]]]b. ∃t [t < t c & ∃t′ [t′≤ t & t′⊆Sunday & ∃s∃e [t′⊂τ(s) & s is a target state of e & P(e)]]Negation and the perfect. We further suggest that the prohibition against RT modification in the perfect is responsible for the fact that the perfect cannot be negated. The negative marker na combines freely with the simple past and present, the past and present progressive, and the past habitual – all tense-aspect forms except for the perfects (Ramchand 2005), see (13) for some representative examples from the non-perfect tense forms. However, the perfect cannot appear with na. Instead of the ungrammatical (14a) we get (14b), where the verb is not explicitly marked for tense and aspect, but is interpreted as past.(13) ami am-Ta { khe-l-am / kha-cch-i / kha-cch-il-am } (na)I mango-cl eat-pst-1 eat-ch-1 eat-ch-pst-1 NEG‘I {did (not) eat / am (not) eating / was (not) eating} the mango.’(14) a. * ami am-Ta { khe-ye-ch-i / khe-ye-ch-il-am} naI mango-class eat-e-ch-1 eat-e-ch-pst-1 NEG‘I {have / had} not eaten the mango.’b. ami am-Ta kha-i-niI mango-class eat -1 -NEG‘I didn’t eat the mango.’The proposal that the na negation in Bangla is a reference time modifier is consistent with the semantics proposed by Ramchand (2005). It is a negative existential quantifier over events asserting that no event of the relevant kind occurs within a specified time interval,i.e., the RT.2。
时间知觉
有关时间知觉的理论：
Figure, The prominent view is that duration encoding depends on dopaminergic striato-frontal mechanisms. Whether the memory and decision stages are subtended by same or different neural circuits is debated. Adapted from (Macar and Vidal, 2004).
时间知觉与空间加工的关系
•视觉通道的时间知觉与客体空间属性的加工密不可分：因为在视觉通道 中对时间进行判断，都首先对客体所占据的空间位置加以编码。
•时间知觉与空间位置编码有交互作用 如：Kappa效应(Price-Williams, 1954)：长的距离产生主观时间延长 tau效应(Helson, 1930)：大的时间间隔产生主观距离变长
有关时间知觉的理论
•传统理论： ‘中央时钟’（‘central clock‘）理论:假设存在一个单一的、
由中枢控制、独立于各感觉通道运行的时间加工系统(Creelman, 1962; Treisman, 1963)
•新理论
•时间知觉是分布式的、与感觉通道紧密融合(Chen, Huang, Luo, Peng, & Liu, 2010; Jantzen, Steinberg, & Kelso, 2005; van Wassenhove, Buonomano, Shimojo, & Shams, 2008)
“在我的手腕上戴着一个感知计时器—— 基本上它就是两块LED屏幕，每块屏幕上 都不断随机闪烁着从1~9的数字。在我被 吊起之前，这个计时器的数 字切换速度 被设定为我刚好无法清楚地读出上面的数 字。如果依格曼的理论是正确的，也就是 在遇到危险时大脑对时间的感知会减慢 【所谓―时间膨胀‖ 】，那么我就应该能够 以一种慢动 作的状态看清上面的数字， 就像是电影《黑客帝国》里面的主角可以 看到飞行的子弹一样。不过前提是，我要 始终睁开我的双眼。”
Empirical processes of dependent random variables
2
Preliminaries
n i=1
from R to R. The centered G -indexed empirical process is given by (P n − P )g = 1 n
n
the marginal and empirical distribution functions. Let G be a class of measurabrocesses that have been discussed include linear processes and Gaussian processes; see Dehling and Taqqu (1989) and Cs¨ org˝ o and Mielniczuk (1996) for long and short-range dependent subordinated Gaussian processes and Ho and Hsing (1996) and Wu (2003a) for long-range dependent linear processes. A collection of recent results is presented in Dehling, Mikosch and Sorensen (2002). In that collection Dedecker and Louhichi (2002) made an important generalization of Ossiander’s (1987) result. Here we investigate the empirical central limit problem for dependent random variables from another angle that avoids strong mixing conditions. In particular, we apply a martingale method and establish a weak convergence theory for stationary, causal processes. Our results are comparable with the theory for independent random variables in that the imposed moment conditions are optimal or almost optimal. We show that, if the process is short-range dependent in a certain sense, then the limiting behavior is similar to that of iid random variables in that the limiting distribution is a Gaussian process and the norming √ sequence is n. For long-range dependent linear processes, one needs to apply asymptotic √ expansions to obtain n-norming limit theorems (Section 6.2.2). The paper is structured as follows. In Section 2 we introduce some mathematical preliminaries necessary for the weak convergence theory and illustrate the essence of our approach. Two types of empirical central limit theorems are established. Empirical processes indexed by indicators of left half lines, absolutely continuous functions, and piecewise differentiable functions are discussed in Sections 3, 4 and 5 respectively. Applications to linear processes and iterated random functions are made in Section 6. Section 7 presents some integral and maximal inequalities that may be of independent interest. Some proofs are given in Sections 8 and 9.
时空中点盘英语
The concept of a time-space midpoint is a theoretical construct rooted deeply in the fabric of astrophysics and theoretical physics, particularly within the realms of Einstein's theory of general relativity. It represents a point where two events or locations in spacetime are equidistant from each other. This essay aims to provide an extensive analysis of this notion, delving into its implications, applications, and the challenges it poses.**Introduction to Spacetime and the Midpoint**In the realm of relativistic physics, space and time are interwoven into a four-dimensional continuum known as 'spacetime'. The time-space midpoint, therefore, signifies a hypothetical point that bisects the spacetime interval between any two events. To calculate this midpoint, one must integrate over both spatial and temporal dimensions, using the metric properties of spacetime which vary according to the distribution of mass-energy within it.**Mathematical Framework**In mathematical terms, given two events (Event A and Event B) characterized by their coordinates in spacetime (xA, yA, zA, tA) and (xB, yB, zB, tB), the spacetime interval Δs² is calculated using the Minkowski metric: Δs² = c²(tB - tA)² - (xB - xA)² - (yB - yA)² - (zB - zA)²The time-space midpoint would then be the event with coordinates such that the spacetime intervals from it to Events A and B are equal. However, unlike the traditional Euclidean midpoint, the calculation is not straightforward due to the non-Euclidean nature of spacetime in the presence of gravity.**Physical Significance**From a physical perspective, the time-space midpoint holds profound implications. It encapsulates the essence of causality in the universe – how one event can influence another across spacetime. For instance, if event A causes event B, the light cone emanating from event A must intersect event B; hence, the midpoint could potentially represent the 'neutral zone' where the causal effect transitions from potential to actual.**Applications in Physics**In gravitational physics, especially in black hole studies, the concept of a time-space midpoint becomes crucial. In the vicinity of a black hole, the curvature of spacetime is so intense that the path connecting two points may involve a traversal through the interior of the black hole itself, altering the traditional definition of a midpoint. This phenomenon is critical for understanding wormholes and the topology of spacetime.Moreover, in cosmology, the idea of a time-space midpoint has relevance in studying the expansion of the universe. It helps in mapping cosmic distances and calculating redshifts, thereby aiding our comprehension of the large-scale structure and evolution of the cosmos.**Challenges and Limitations**Despite its conceptual elegance, finding the exact time-space midpoint presents several challenges. Due to the non-linearity of general relativity, solving for midpoints often requires complex numerical simulations or approximations. Also, quantum effects at extremely small scales can significantly alter spacetime geometry, introducing further complexity.Furthermore, the reality of faster-than-light travel or information transfer remains speculative. If such phenomena were possible, they would redefine the very concept of a midpoint since it would allow shortcuts through spacetime, bypassing the traditional geometric interpretation.**Conclusion**The time-space midpoint, while abstract and mathematically intricate, is a fundamental concept in modern physics. Its exploration pushes the boundaries of our understanding of the universe, challenging us to refine our theories and computational methods. Despite the hurdles, it continues to illuminate paths towards unraveling the mysteries of spacetime, causality, and the fundamental workings of the cosmos. The quest for the time-space midpoint is thus an ongoing journey in the relentless pursuit of scientific truth.This discussion barely scratches the surface of the topic, yet it underscores the depth and breadth of the subject matter. Expanding on these themes requiresmore than 1340 words, but this primer serves as a starting point for a comprehensive, multifaceted analysis of the time-space midpoint in the broader context of contemporary physics.(Word Count: ~580)*(Please note that this is a summarized version and expanding upon each section with detailed explanations and examples will exceed the 1340-word limit as required.)*。
毕业设计论文塑料注射成型
Modeling of morphology evolution in the injection moldingprocess of thermoplastic polymersR.Pantani,I.Coccorullo,V.Speranza,G.Titomanlio* Department of Chemical and Food Engineering,University of Salerno,via Ponte don Melillo,I-84084Fisciano(Salerno),Italy Received13May2005;received in revised form30August2005;accepted12September2005AbstractA thorough analysis of the effect of operative conditions of injection molding process on the morphology distribution inside the obtained moldings is performed,with particular reference to semi-crystalline polymers.The paper is divided into two parts:in the first part,the state of the art on the subject is outlined and discussed;in the second part,an example of the characterization required for a satisfactorily understanding and description of the phenomena is presented,starting from material characterization,passing through the monitoring of the process cycle and arriving to a deep analysis of morphology distribution inside the moldings.In particular,fully characterized injection molding tests are presented using an isotactic polypropylene,previously carefully characterized as far as most of properties of interest.The effects of both injectionflow rate and mold temperature are analyzed.The resulting moldings morphology(in terms of distribution of crystallinity degree,molecular orientation and crystals structure and dimensions)are analyzed by adopting different experimental techniques(optical,electronic and atomic force microscopy,IR and WAXS analysis).Final morphological characteristics of the samples are compared with the predictions of a simulation code developed at University of Salerno for the simulation of the injection molding process.q2005Elsevier Ltd.All rights reserved.Keywords:Injection molding;Crystallization kinetics;Morphology;Modeling;Isotactic polypropyleneContents1.Introduction (1186)1.1.Morphology distribution in injection molded iPP parts:state of the art (1189)1.1.1.Modeling of the injection molding process (1190)1.1.2.Modeling of the crystallization kinetics (1190)1.1.3.Modeling of the morphology evolution (1191)1.1.4.Modeling of the effect of crystallinity on rheology (1192)1.1.5.Modeling of the molecular orientation (1193)1.1.6.Modeling of theflow-induced crystallization (1195)ments on the state of the art (1197)2.Material and characterization (1198)2.1.PVT description (1198)*Corresponding author.Tel.:C39089964152;fax:C39089964057.E-mail address:gtitomanlio@unisa.it(G.Titomanlio).2.2.Quiescent crystallization kinetics (1198)2.3.Viscosity (1199)2.4.Viscoelastic behavior (1200)3.Injection molding tests and analysis of the moldings (1200)3.1.Injection molding tests and sample preparation (1200)3.2.Microscopy (1202)3.2.1.Optical microscopy (1202)3.2.2.SEM and AFM analysis (1202)3.3.Distribution of crystallinity (1202)3.3.1.IR analysis (1202)3.3.2.X-ray analysis (1203)3.4.Distribution of molecular orientation (1203)4.Analysis of experimental results (1203)4.1.Injection molding tests (1203)4.2.Morphology distribution along thickness direction (1204)4.2.1.Optical microscopy (1204)4.2.2.SEM and AFM analysis (1204)4.3.Morphology distribution alongflow direction (1208)4.4.Distribution of crystallinity (1210)4.4.1.Distribution of crystallinity along thickness direction (1210)4.4.2.Crystallinity distribution alongflow direction (1212)4.5.Distribution of molecular orientation (1212)4.5.1.Orientation along thickness direction (1212)4.5.2.Orientation alongflow direction (1213)4.5.3.Direction of orientation (1214)5.Simulation (1214)5.1.Pressure curves (1215)5.2.Morphology distribution (1215)5.3.Molecular orientation (1216)5.3.1.Molecular orientation distribution along thickness direction (1216)5.3.2.Molecular orientation distribution alongflow direction (1216)5.3.3.Direction of orientation (1217)5.4.Crystallinity distribution (1217)6.Conclusions (1217)References (1219)1.IntroductionInjection molding is one of the most widely employed methods for manufacturing polymeric products.Three main steps are recognized in the molding:filling,packing/holding and cooling.During thefilling stage,a hot polymer melt rapidlyfills a cold mold reproducing a cavity of the desired product shape. During the packing/holding stage,the pressure is raised and extra material is forced into the mold to compensate for the effects that both temperature decrease and crystallinity development determine on density during solidification.The cooling stage starts at the solidification of a thin section at cavity entrance (gate),starting from that instant no more material can enter or exit from the mold impression and holding pressure can be released.When the solid layer on the mold surface reaches a thickness sufficient to assure required rigidity,the product is ejected from the mold.Due to the thermomechanical history experienced by the polymer during processing,macromolecules in injection-molded objects present a local order.This order is referred to as‘morphology’which literally means‘the study of the form’where form stands for the shape and arrangement of parts of the object.When referred to polymers,the word morphology is adopted to indicate:–crystallinity,which is the relative volume occupied by each of the crystalline phases,including mesophases;–dimensions,shape,distribution and orientation of the crystallites;–orientation of amorphous phase.R.Pantani et al./Prog.Polym.Sci.30(2005)1185–1222 1186R.Pantani et al./Prog.Polym.Sci.30(2005)1185–12221187Apart from the scientific interest in understandingthe mechanisms leading to different order levels inside a polymer,the great technological importance of morphology relies on the fact that polymer character-istics (above all mechanical,but also optical,electrical,transport and chemical)are to a great extent affected by morphology.For instance,crystallinity has a pro-nounced effect on the mechanical properties of the bulk material since crystals are generally stiffer than amorphous material,and also orientation induces anisotropy and other changes in mechanical properties.In this work,a thorough analysis of the effect of injection molding operative conditions on morphology distribution in moldings with particular reference to crystalline materials is performed.The aim of the paper is twofold:first,to outline the state of the art on the subject;second,to present an example of the characterization required for asatisfactorilyR.Pantani et al./Prog.Polym.Sci.30(2005)1185–12221188understanding and description of the phenomena, starting from material description,passing through the monitoring of the process cycle and arriving to a deep analysis of morphology distribution inside the mold-ings.To these purposes,fully characterized injection molding tests were performed using an isotactic polypropylene,previously carefully characterized as far as most of properties of interest,in particular quiescent nucleation density,spherulitic growth rate and rheological properties(viscosity and relaxation time)were determined.The resulting moldings mor-phology(in terms of distribution of crystallinity degree, molecular orientation and crystals structure and dimensions)was analyzed by adopting different experimental techniques(optical,electronic and atomic force microscopy,IR and WAXS analysis).Final morphological characteristics of the samples were compared with the predictions of a simulation code developed at University of Salerno for the simulation of the injection molding process.The effects of both injectionflow rate and mold temperature were analyzed.1.1.Morphology distribution in injection molded iPP parts:state of the artFrom many experimental observations,it is shown that a highly oriented lamellar crystallite microstructure, usually referred to as‘skin layer’forms close to the surface of injection molded articles of semi-crystalline polymers.Far from the wall,the melt is allowed to crystallize three dimensionally to form spherulitic structures.Relative dimensions and morphology of both skin and core layers are dependent on local thermo-mechanical history,which is characterized on the surface by high stress levels,decreasing to very small values toward the core region.As a result,the skin and the core reveal distinct characteristics across the thickness and also along theflow path[1].Structural and morphological characterization of the injection molded polypropylene has attracted the interest of researchers in the past three decades.In the early seventies,Kantz et al.[2]studied the morphology of injection molded iPP tensile bars by using optical microscopy and X-ray diffraction.The microscopic results revealed the presence of three distinct crystalline zones on the cross-section:a highly oriented non-spherulitic skin;a shear zone with molecular chains oriented essentially parallel to the injection direction;a spherulitic core with essentially no preferred orientation.The X-ray diffraction studies indicated that the skin layer contains biaxially oriented crystallites due to the biaxial extensionalflow at theflow front.A similar multilayered morphology was also reported by Menges et al.[3].Later on,Fujiyama et al.[4] investigated the skin–core morphology of injection molded iPP samples using X-ray Small and Wide Angle Scattering techniques,and suggested that the shear region contains shish–kebab structures.The same shish–kebab structure was observed by Wenig and Herzog in the shear region of their molded samples[5].A similar investigation was conducted by Titomanlio and co-workers[6],who analyzed the morphology distribution in injection moldings of iPP. They observed a skin–core morphology distribution with an isotropic spherulitic core,a skin layer characterized by afine crystalline structure and an intermediate layer appearing as a dark band in crossed polarized light,this layer being characterized by high crystallinity.Kalay and Bevis[7]pointed out that,although iPP crystallizes essentially in the a-form,a small amount of b-form can be found in the skin layer and in the shear region.The amount of b-form was found to increase by effect of high shear rates[8].A wide analysis on the effect of processing conditions on the morphology of injection molded iPP was conducted by Viana et al.[9]and,more recently, by Mendoza et al.[10].In particular,Mendoza et al. report that the highest level of crystallinity orientation is found inside the shear zone and that a high level of orientation was also found in the skin layer,with an orientation angle tilted toward the core.It is rather difficult to theoretically establish the relationship between the observed microstructure and processing conditions.Indeed,a model of the injection molding process able to predict morphology distribution in thefinal samples is not yet available,even if it would be of enormous strategic importance.This is mainly because a complete understanding of crystallization kinetics in processing conditions(high cooling rates and pressures,strong and complexflowfields)has not yet been reached.In this section,the most relevant aspects for process modeling and morphology development are identified. In particular,a successful path leading to a reliable description of morphology evolution during polymer processing should necessarily pass through:–a good description of morphology evolution under quiescent conditions(accounting all competing crystallization processes),including the range of cooling rates characteristic of processing operations (from1to10008C/s);R.Pantani et al./Prog.Polym.Sci.30(2005)1185–12221189–a description capturing the main features of melt morphology(orientation and stretch)evolution under processing conditions;–a good coupling of the two(quiescent crystallization and orientation)in order to capture the effect of crystallinity on viscosity and the effect offlow on crystallization kinetics.The points listed above outline the strategy to be followed in order to achieve the basic understanding for a satisfactory description of morphology evolution during all polymer processing operations.In the following,the state of art for each of those points will be analyzed in a dedicated section.1.1.1.Modeling of the injection molding processThefirst step in the prediction of the morphology distribution within injection moldings is obviously the thermo-mechanical simulation of the process.Much of the efforts in the past were focused on the prediction of pressure and temperature evolution during the process and on the prediction of the melt front advancement [11–15].The simulation of injection molding involves the simultaneous solution of the mass,energy and momentum balance equations.Thefluid is non-New-tonian(and viscoelastic)with all parameters dependent upon temperature,pressure,crystallinity,which are all function of pressibility cannot be neglected as theflow during the packing/holding step is determined by density changes due to temperature, pressure and crystallinity evolution.Indeed,apart from some attempts to introduce a full 3D approach[16–19],the analysis is currently still often restricted to the Hele–Shaw(or thinfilm) approximation,which is warranted by the fact that most injection molded parts have the characteristic of being thin.Furthermore,it is recognized that the viscoelastic behavior of the polymer only marginally influences theflow kinematics[20–22]thus the melt is normally considered as a non-Newtonian viscousfluid for the description of pressure and velocity gradients evolution.Some examples of adopting a viscoelastic constitutive equation in the momentum balance equations are found in the literature[23],but the improvements in accuracy do not justify a considerable extension of computational effort.It has to be mentioned that the analysis of some features of kinematics and temperature gradients affecting the description of morphology need a more accurate description with respect to the analysis of pressure distributions.Some aspects of the process which were often neglected and may have a critical importance are the description of the heat transfer at polymer–mold interface[24–26]and of the effect of mold deformation[24,27,28].Another aspect of particular interest to the develop-ment of morphology is the fountainflow[29–32], which is often neglected being restricted to a rather small region at theflow front and close to the mold walls.1.1.2.Modeling of the crystallization kineticsIt is obvious that the description of crystallization kinetics is necessary if thefinal morphology of the molded object wants to be described.Also,the development of a crystalline degree during the process influences the evolution of all material properties like density and,above all,viscosity(see below).Further-more,crystallization kinetics enters explicitly in the generation term of the energy balance,through the latent heat of crystallization[26,33].It is therefore clear that the crystallinity degree is not only a result of simulation but also(and above all)a phenomenon to be kept into account in each step of process modeling.In spite of its dramatic influence on the process,the efforts to simulate the injection molding of semi-crystalline polymers are crude in most of the commercial software for processing simulation and rather scarce in the fleur and Kamal[34],Papatanasiu[35], Titomanlio et al.[15],Han and Wang[36],Ito et al.[37],Manzione[38],Guo and Isayev[26],and Hieber [25]adopted the following equation(Kolmogoroff–Avrami–Evans,KAE)to predict the development of crystallinityd xd tZð1K xÞd d cd t(1)where x is the relative degree of crystallization;d c is the undisturbed volume fraction of the crystals(if no impingement would occur).A significant improvement in the prediction of crystallinity development was introduced by Titoman-lio and co-workers[39]who kept into account the possibility of the formation of different crystalline phases.This was done by assuming a parallel of several non-interacting kinetic processes competing for the available amorphous volume.The evolution of each phase can thus be described byd x id tZð1K xÞd d c id t(2)where the subscript i stands for a particular phase,x i is the relative degree of crystallization,x ZPix i and d c iR.Pantani et al./Prog.Polym.Sci.30(2005)1185–1222 1190is the expectancy of volume fraction of each phase if no impingement would occur.Eq.(2)assumes that,for each phase,the probability of the fraction increase of a single crystalline phase is simply the product of the rate of growth of the corresponding undisturbed volume fraction and of the amount of available amorphous fraction.By summing up the phase evolution equations of all phases(Eq.(2))over the index i,and solving the resulting differential equation,one simply obtainsxðtÞZ1K exp½K d cðtÞ (3)where d c Z Pid c i and Eq.(1)is recovered.It was shown by Coccorullo et al.[40]with reference to an iPP,that the description of the kinetic competition between phases is crucial to a reliable prediction of solidified structures:indeed,it is not possible to describe iPP crystallization kinetics in the range of cooling rates of interest for processing(i.e.up to several hundreds of8C/s)if the mesomorphic phase is neglected:in the cooling rate range10–1008C/s, spherulite crystals in the a-phase are overcome by the formation of the mesophase.Furthermore,it has been found that in some conditions(mainly at pressures higher than100MPa,and low cooling rates),the g-phase can also form[41].In spite of this,the presence of different crystalline phases is usually neglected in the literature,essentially because the range of cooling rates investigated for characterization falls in the DSC range (well lower than typical cooling rates of interest for the process)and only one crystalline phase is formed for iPP at low cooling rates.It has to be noticed that for iPP,which presents a T g well lower than ambient temperature,high values of crystallinity degree are always found in solids which passed through ambient temperature,and the cooling rate can only determine which crystalline phase forms, roughly a-phase at low cooling rates(below about 508C/s)and mesomorphic phase at higher cooling rates.The most widespread approach to the description of kinetic constant is the isokinetic approach introduced by Nakamura et al.According to this model,d c in Eq.(1)is calculated asd cðtÞZ ln2ðt0KðTðsÞÞd s2 435n(4)where K is the kinetic constant and n is the so-called Avrami index.When introduced as in Eq.(4),the reciprocal of the kinetic constant is a characteristic time for crystallization,namely the crystallization half-time, t05.If a polymer is cooled through the crystallization temperature,crystallization takes place at the tempera-ture at which crystallization half-time is of the order of characteristic cooling time t q defined ast q Z D T=q(5) where q is the cooling rate and D T is a temperature interval over which the crystallization kinetic constant changes of at least one order of magnitude.The temperature dependence of the kinetic constant is modeled using some analytical function which,in the simplest approach,is described by a Gaussian shaped curve:KðTÞZ K0exp K4ln2ðT K T maxÞ2D2(6)The following Hoffman–Lauritzen expression[42] is also commonly adopted:K½TðtÞ Z K0exp KUÃR$ðTðtÞK T NÞ!exp KKÃ$ðTðtÞC T mÞ2TðtÞ2$ðT m K TðtÞÞð7ÞBoth equations describe a bell shaped curve with a maximum which for Eq.(6)is located at T Z T max and for Eq.(7)lies at a temperature between T m(the melting temperature)and T N(which is classically assumed to be 308C below the glass transition temperature).Accord-ing to Eq.(7),the kinetic constant is exactly zero at T Z T m and at T Z T N,whereas Eq.(6)describes a reduction of several orders of magnitude when the temperature departs from T max of a value higher than2D.It is worth mentioning that only three parameters are needed for Eq.(6),whereas Eq.(7)needs the definition offive parameters.Some authors[43,44]couple the above equations with the so-called‘induction time’,which can be defined as the time the crystallization process starts, when the temperature is below the equilibrium melting temperature.It is normally described as[45]Dt indDtZðT0m K TÞat m(8)where t m,T0m and a are material constants.It should be mentioned that it has been found[46,47]that there is no need to explicitly incorporate an induction time when the modeling is based upon the KAE equation(Eq.(1)).1.1.3.Modeling of the morphology evolutionDespite of the fact that the approaches based on Eq.(4)do represent a significant step toward the descriptionR.Pantani et al./Prog.Polym.Sci.30(2005)1185–12221191of morphology,it has often been pointed out in the literature that the isokinetic approach on which Nakamura’s equation (Eq.(4))is based does not describe details of structure formation [48].For instance,the well-known experience that,with many polymers,the number of spherulites in the final solid sample increases strongly with increasing cooling rate,is indeed not taken into account by this approach.Furthermore,Eq.(4)describes an increase of crystal-linity (at constant temperature)depending only on the current value of crystallinity degree itself,whereas it is expected that the crystallization rate should depend also on the number of crystalline entities present in the material.These limits are overcome by considering the crystallization phenomenon as the consequence of nucleation and growth.Kolmogoroff’s model [49],which describes crystallinity evolution accounting of the number of nuclei per unit volume and spherulitic growth rate can then be applied.In this case,d c in Eq.(1)is described asd ðt ÞZ C m ðt 0d N ðs Þd s$ðt sG ðu Þd u 2435nd s (9)where C m is a shape factor (C 3Z 4/3p ,for spherical growth),G (T (t ))is the linear growth rate,and N (T (t ))is the nucleation density.The following Hoffman–Lauritzen expression is normally adopted for the growth rateG ½T ðt Þ Z G 0exp KUR $ðT ðt ÞK T N Þ!exp K K g $ðT ðt ÞC T m Þ2T ðt Þ2$ðT m K T ðt ÞÞð10ÞEqs.(7)and (10)have the same form,however the values of the constants are different.The nucleation mechanism can be either homo-geneous or heterogeneous.In the case of heterogeneous nucleation,two equations are reported in the literature,both describing the nucleation density as a function of temperature [37,50]:N ðT ðt ÞÞZ N 0exp ½j $ðT m K T ðt ÞÞ (11)N ðT ðt ÞÞZ N 0exp K 3$T mT ðt ÞðT m K T ðt ÞÞ(12)In the case of homogeneous nucleation,the nucleation rate rather than the nucleation density is function of temperature,and a Hoffman–Lauritzen expression isadoptedd N ðT ðt ÞÞd t Z N 0exp K C 1ðT ðt ÞK T N Þ!exp KC 2$ðT ðt ÞC T m ÞT ðt Þ$ðT m K T ðt ÞÞð13ÞConcentration of nucleating particles is usually quite significant in commercial polymers,and thus hetero-geneous nucleation becomes the dominant mechanism.When Kolmogoroff’s approach is followed,the number N a of active nuclei at the end of the crystal-lization process can be calculated as [48]N a ;final Zðt final 0d N ½T ðs Þd sð1K x ðs ÞÞd s (14)and the average dimension of crystalline structures can be attained by geometrical considerations.Pantani et al.[51]and Zuidema et al.[22]exploited this method to describe the distribution of crystallinity and the final average radius of the spherulites in injection moldings of polypropylene;in particular,they adopted the following equationR Z ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi3x a ;final 4p N a ;final 3s (15)A different approach is also present in the literature,somehow halfway between Nakamura’s and Kolmo-goroff’s models:the growth rate (G )and the kinetic constant (K )are described independently,and the number of active nuclei (and consequently the average dimensions of crystalline entities)can be obtained by coupling Eqs.(4)and (9)asN a ðT ÞZ 3ln 24p K ðT ÞG ðT Þ 3(16)where heterogeneous nucleation and spherical growth is assumed (Avrami’s index Z 3).Guo et al.[43]adopted this approach to describe the dimensions of spherulites in injection moldings of polypropylene.1.1.4.Modeling of the effect of crystallinity on rheology As mentioned above,crystallization has a dramatic influence on material viscosity.This phenomenon must obviously be taken into account and,indeed,the solidification of a semi-crystalline material is essen-tially caused by crystallization rather than by tempera-ture in normal processing conditions.Despite of the importance of the subject,the relevant literature on the effect of crystallinity on viscosity isR.Pantani et al./Prog.Polym.Sci.30(2005)1185–12221192rather scarce.This might be due to the difficulties in measuring simultaneously rheological properties and crystallinity evolution during the same tests.Apart from some attempts to obtain simultaneous measure-ments of crystallinity and viscosity by special setups [52,53],more often viscosity and crystallinity are measured during separate tests having the same thermal history,thus greatly simplifying the experimental approach.Nevertheless,very few works can be retrieved in the literature in which(shear or complex) viscosity can be somehow linked to a crystallinity development.This is the case of Winter and co-workers [54],Vleeshouwers and Meijer[55](crystallinity evolution can be drawn from Swartjes[56]),Boutahar et al.[57],Titomanlio et al.[15],Han and Wang[36], Floudas et al.[58],Wassner and Maier[59],Pantani et al.[60],Pogodina et al.[61],Acierno and Grizzuti[62].All the authors essentially agree that melt viscosity experiences an abrupt increase when crystallinity degree reaches a certain‘critical’value,x c[15]. However,little agreement is found in the literature on the value of this critical crystallinity degree:assuming that x c is reached when the viscosity increases of one order of magnitude with respect to the molten state,it is found in the literature that,for iPP,x c ranges from a value of a few percent[15,62,60,58]up to values of20–30%[58,61]or even higher than40%[59,54,57].Some studies are also reported on the secondary effects of relevant variables such as temperature or shear rate(or frequency)on the dependence of crystallinity on viscosity.As for the effect of temperature,Titomanlio[15]found for an iPP that the increase of viscosity for the same crystallinity degree was higher at lower temperatures,whereas Winter[63] reports the opposite trend for a thermoplastic elasto-meric polypropylene.As for the effect of shear rate,a general agreement is found in the literature that the increase of viscosity for the same crystallinity degree is lower at higher deformation rates[62,61,57].Essentially,the equations adopted to describe the effect of crystallinity on viscosity of polymers can be grouped into two main categories:–equations based on suspensions theories(for a review,see[64]or[65]);–empirical equations.Some of the equations adopted in the literature with regard to polymer processing are summarized in Table1.Apart from Eq.(17)adopted by Katayama and Yoon [66],all equations predict a sharp increase of viscosity on increasing crystallinity,sometimes reaching infinite (Eqs.(18)and(21)).All authors consider that the relevant variable is the volume occupied by crystalline entities(i.e.x),even if the dimensions of the crystals should reasonably have an effect.1.1.5.Modeling of the molecular orientationOne of the most challenging problems to present day polymer science regards the reliable prediction of molecular orientation during transformation processes. Indeed,although pressure and velocity distribution during injection molding can be satisfactorily described by viscous models,details of the viscoelastic nature of the polymer need to be accounted for in the descriptionTable1List of the most used equations to describe the effect of crystallinity on viscosityEquation Author Derivation Parameters h=h0Z1C a0x(17)Katayama[66]Suspensions a Z99h=h0Z1=ðx K x cÞa0(18)Ziabicki[67]Empirical x c Z0.1h=h0Z1C a1expðK a2=x a3Þ(19)Titomanlio[15],also adopted byGuo[68]and Hieber[25]Empiricalh=h0Z expða1x a2Þ(20)Shimizu[69],also adopted byZuidema[22]and Hieber[25]Empiricalh=h0Z1Cðx=a1Þa2=ð1Kðx=a1Þa2Þ(21)Tanner[70]Empirical,basedon suspensionsa1Z0.44for compact crystallitesa1Z0.68for spherical crystallitesh=h0Z expða1x C a2x2Þ(22)Han[36]Empiricalh=h0Z1C a1x C a2x2(23)Tanner[71]Empirical a1Z0.54,a2Z4,x!0.4h=h0Zð1K x=a0ÞK2(24)Metzner[65],also adopted byTanner[70]Suspensions a Z0.68for smooth spheresR.Pantani et al./Prog.Polym.Sci.30(2005)1185–12221193。
ISO8201-1987声学.可听见的紧急撤离信号-GZ
and the required sound pressure level at all places within the evacuation signal be recognizable,
be able to “penetrate” all background noises and frequency patterns. For this reason it seemed prudent to select the kind of sound best able to “penetrate” noise pattern unique and recognizable Frequently already understandable pattern audibly a particular background by imposing on it a standard in a given building and then to make that sound of “on” and “off” times.
the member bodies for approval before their acceptance the IS0 Council. They are approved in accordance least 75 % approval by the member bodies voting.
Acoustics
-
Audible
emergency
evacuation
signal
Acoustique
-
Signal sonore d’bvacuation
d’urgence
Reference number IS0 8201:1987 (E)
Probability and Stochastic Processes
Probability and Stochastic Processes Probability and stochastic processes are fundamental concepts in the field of mathematics and have wide-ranging applications in various fields such as engineering, finance, and science. Understanding these concepts is crucial for making informed decisions in uncertain and random environments. In this response, we will delve into the significance of probability and stochastic processes, their real-world applications, and the challenges associated with studying and applying these concepts. Probability is the branch of mathematics that deals with the likelihood of a particular event or outcome occurring. It provides a framework for quantifying uncertainty and making predictions based on available information. Stochastic processes, on the other hand, are mathematical models that describe the evolution of random variables over time. These processes are used to analyze and predict the behavior of complex systems that exhibit random behavior. One of the key reasons why probability and stochastic processes are important is their role in decision-making under uncertainty. In many real-world scenarios, decisions need to be made in the presence of incomplete information and unpredictable outcomes. Probability theory provides a systematic way to evaluate the likelihood of different outcomes and make rational decisions based on this assessment. Stochastic processes, on the other hand, are used to model and analyze random phenomena such as stock prices, weather patterns, and the spread of diseases. In the field of engineering, probability and stochastic processes are used to design and analyze systems that operate in uncertain environments. For example, in the design of communication systems, engineers use probability theory to analyze the performance of error-correcting codes and stochastic processes to model the behavior of wireless channels. Similarly, in the field of finance, these concepts are used to model the behavior of financial markets, price derivatives, and manage risk. Despite their wide-ranging applications, studying probability and stochastic processes can be challenging due to their abstract nature and the need for a strong mathematical foundation. Many students find it difficult to grasp the concepts of probability, random variables, and stochastic processes, as they often require a shift in thinking from deterministic to probabilistic reasoning. Moreover, the mathematical tools and techniques used to analyze these concepts,such as measure theory and stochastic calculus, can be quite advanced and require a significant amount of time and effort to master. In addition to the academic challenges, there are also practical difficulties in applying probability and stochastic processes to real-world problems. For example, in financial modeling, accurately predicting stock prices or interest rates using stochastic processes is a complex task that requires sophisticated mathematical models and large amounts of historical data. Furthermore, the assumptions made in these models, such as the independence of random variables or the stationarity of processes, may not always hold in practice, leading to inaccuracies in predictions. In conclusion, probability and stochastic processes are essential tools for understanding and navigating the uncertainties of the world. From decision-making under uncertainty to modeling complex systems, these concepts play a crucial role in a wide range of fields. However, mastering these concepts and applying them to real-world problems can be challenging due to their abstract nature and the complexity of the mathematical techniques involved. Nonetheless, the rewards of understanding and applying probability and stochastic processes are immense, as they provide a powerful framework for making informed decisions and predicting the behavior of random phenomena.。
心脏超声中英文对照词汇
Pericardial effusion
心包积液
Pericardial effusion
心外膜冠状动脉
Epicardial coronary artery
心尖多孔瑞士奶酪样室间隔缺损
Digital multiple swiss cheese septal defect
心肌内冠状动脉
Intramyocardial coronary artery
经食道超声心动图
Transesophagealechocardiography
限制性室间隔缺损
Restrictive ventricular septal defect
非致密性心室心肌二维超声心动图
Non-compaction of ventricular myocardium two dimensional echocardiography
心肌对比超声心动图
Myocardial contrast echocardiography，MCE
心肌梗塞
Myocardial infarction
心肌梗塞并发症
Complications of myocardialinfarction
心房内血栓
Atria thrombus
心房黏液瘤
Atria myxoma，MYX
Congenital pulmonary artery fistula
先天性冠状动脉瘘
Congenital coronary artery fistula
共振
Resonant
共振频率
Resonant frenquency
压力半降时间
Pressure half-time，PHT
自然语言时间语义信息处理
第三章时间信息表达与推理模型
行为描述是指对于概念的行为进行形式化的描述，概念网络目前采用的是脚本描述方法，这种方法简单方便，而且推理链可以清晰呈现，虽然描述的灵活性不够，效率需要进一步提高，但已经可以基本实现对于现代汉语中虚词行为规则的有效分析和描述。
基于此，对于自然语言中实词和虚词两大词类，都有了相应的语义处理方法，并可以实现对于句子的统一分析：分词之后，首先确定词汇对应的概念，然后通过概念复合规则对相关概念进行语义复合，接着进一步分析概念类脚本的执行和成员脚本的执行，达到对语义的初步分析处理。
概念网络不仅仅是一种知识表示方法，而且已经搭建起了概念网络平台。
概念平台将概念按照领域区分存放，加载了特定领域的概念库之后，便可以对相应的领域概念的属性、行为等特征进行编辑，添加概念之间的语义状态、语义约束等相关语义联系。
由于目前概念网络平台的概念语义知识有限，还无法达到自动分析获取语义的阶段，因此初期为了确保准确性，采用手工添加概念语义特征的方法。
在此实验平台之上，当构建了比较丰富的语义之后，可以进一步添加自动学习的方法，分析语料的语义关联，以自动获取概念语义定义。
概念平台中除了概念的定义和浏览模块，还增加了中文文本分词，文本理解接口，初步实现了对已定义概念的语义复合功能，参见图３—２。
３—２概念网络语义处理平台。
适用于轴承故障诊断的数据增强算法
2021577轴承故障诊断在制造业的故障预测和健康管理中起着十分重要的作用。
除了传统的故障诊断方法以外，学者们将改进过的机器学习[1-4]和深度学习算法[5-8]应用于故障诊断领域，其诊断效率与准确率得到了较大的提高。
在大部分应用中，这些算法有两个共同点[9]：第一、根据经验风险最小化原则（Empirical Risk Minimization，ERM）[10]训练故障诊断模型。
第二、使用此原则训练的诊断模型的性能优劣主要取决于所使用的训练样本的数量和质量。
但在工业应用中，数据集中正负样本的比例不平衡：故障数据包含着区分类别的有用信息，但是所占比例较少。
此外由于机器的载荷、转轴转速等工况的不同，所记录的数据并不服从ERM原则中的独立同分布假设。
这两点使得ERM原则不适用于训练工业实际场景中的故障诊断模型，并且文献[11]表明使用ERM原则训练的模型无法拥有较好的泛化性能。
数据增强算法是邻域风险最小化原则[12]（Vicinal Risk Minimization，VRM）的实现方式之一，能够缓解ERM原则所带来的问题。
在VRM中通过先验知识来构建每个训练样本周围的领域区域，然后可从训练样本的领域分布中获取额外的模拟样本来扩充数据集。
例如，对于图像分类来说，通过将一个图片的领域定义为其经过平移、旋转、翻转、裁剪等变化之后的集合。
但与机器学习/深度学习中的数据不同，故障诊断中的数据（例如轴承故障诊断中的振动信号）具有明显的物理意义和机理特征，适用于机器视觉的数据增强方法可能导致物理意义的改变。
因此，本文从信号处理和信号分析的角度出发，设计了一种适用于轴承故障诊断中振动信号的数据增强方法。
适用于轴承故障诊断的数据增强算法林荣来，汤冰影，陈明同济大学机械与能源工程学院，上海201804摘要：针对在轴承故障诊断中存在的故障数据较少、数据所属工况较多的问题，提出了一种基于阶次跟踪的数据增强算法。
该算法利用阶次跟踪中的角域不变性，对原始振动信号进行时域重采样从而生成模拟信号，随后重新计算信号的幅值来抵消时域重采样以及环境噪声对原始信号能量的影响，最后使用随机零填充来保证信号在变化过程中采样长度不变。
间歇前抑制惊跳反射在听觉科学领域的研究进展
戴晨逸 徐飞DAI Chen-yi, XU Fei间歇前抑制惊跳反射在听觉科学领域的研究进展作者单位：浙江中医药大学 杭州 310053作者简介：戴晨逸 本科；研究方向：听力学通讯作者：徐飞，E-mail:***********.cn间歇前抑制惊跳反射（gap prepulse inhibition of acoustic startle response，GPIAS）也称间隙前脉冲抑制（gap induced pre-pulse inhibition，Gap-PPI），它是听觉惊跳反射前刺激抑制（prepulse inhibition of acoustic startle response，PPI）的特殊形式，其产生基础来自听觉惊跳反射（acoustic startle response，ASR）。
Gap-PPI与PPI的神经通路不相同，两者不能混为一谈。
Gap-PPI目前常用于听觉研究领域和精神疾病研究，它是一种有效且便捷的评估动物听觉系统乃至相关神经系统的客观测试方法，来自于动物的先天性反射行为，不需要进行提前训练，因此测试结果具有较好的稳定性和可靠性。
本文对Gap-PPI的背景、影响因素及听觉系统相关应用进行综述。
1 间歇前抑制惊跳反射与惊跳反射、前抑制惊跳发射听觉惊跳反射是人类或哺乳类动物在受到外界声刺激时出于本能的自卫反应引起的肌肉快速收缩。
Research Progress on Gap Prepulse Inhibition of Acoustic Startle Responsein the Field of Auditory Science【摘要】 间歇前抑制惊跳反射（gap prepulse inhibition of acoustic startle response,GPIAS）是一种有效且便捷的评估动物听觉系统乃至相关神经系统的客观测试方法，目前常用于听觉领域和精神疾病的研究。
小区保洁各岗位时间节点工作流程
英文回答：The workflow for the residential area cleaning staff epasses a series of scheduled tasks and job responsibilities. At themencement of their shift, it is imperative for the staff to conduct aprehensive inspection of the entire area, in order to identify and address any immediate concerns such as litter or debris. Subsequently, they are tasked with the thorough sweeping and cleansing ofmunal areas including entrances, hallways, and outdoor spaces. This phase is pivotal in ensuring that the surroundings are maintained in a pristine and inviting condition for the residents and visitors throughout the duration of the day.住宅区清洁工作人员的工作流程通过一系列预定任务和工作责任。
工作人员在值班时必须对整个地区进行全面视察，以查明和处理诸如垃圾或碎片等直接关切问题。
随后，他们负责彻底扫清包括入口、走廊和户外空间在内的免疫区。
这一阶段对于确保周围环境保持纯洁和在全天期间为居民和游客提供客房条件至关重要。
During the middle of the day, the cleaning crew will focus on specific tasks like taking out the trash, cleaning the public bathrooms, and handling any ongoing maintenance stuff. It'salso a good time for them to fill up supplies like toilet paper and cleaning products in themon areas. They need to be around all day to deal with any new messes or problems thate up.在白天，清洁人员将专注于一些具体的任务，例如清除垃圾，清洗公共浴室，以及处理任何正在进行的维修工作。
时间给了我答案作文200字左右
时间给了我答案作文200字左右英文回答：In the labyrinth of time, the answers to life's enigmatic queries lie concealed, waiting to be unraveled. Time, an enigmatic entity, both a healer and a destroyer, holds the power to shape our destinies and reveal truths that may have otherwise remained hidden. As we traverse the annals of time, we accumulate experiences that mold our perspectives and illuminate the path before us.Through the passage of time, we witness the rise and fall of civilizations, the ebb and flow of human emotions, and the relentless progression of our own lives. It is within these temporal intervals that we discover the resilience of the human spirit, the fragility of existence, and the interconnectedness of all things. Time serves as a catalyst for personal growth, etching wisdom upon our hearts and expanding our understanding of the world around us.As the sands of time relentlessly slip away, they carry with them the memories of our triumphs and tribulations, leaving behind a tapestry woven with the threads of our past. By reflecting upon these experiences, we gain invaluable insights into our strengths and weaknesses, fostering a deeper sense of self-awareness. Time allows us to heal from wounds, both physical and emotional, granting us the opportunity to emerge from adversity with newfound resilience and compassion.Yet, the passage of time can also be a source of regret and loss. As we bid farewell to loved ones and witness the fading of youthful dreams, the weight of time's inexorable march can bear down upon our souls. It is in these moments that we must find solace in the ephemeral nature of existence, embracing the brevity of our time on Earth and cherishing the precious bonds that we forge along the way.Time, like a skilled craftsman, chisels away at the rough edges of our being, revealing the beauty and depth that lie within. Through its relentless passage, it shapesour character, deepens our understanding, and ultimately prepares us for the inevitable journey that lies ahead.中文回答：时间给了我答案。
对地观测小卫星星座长期任务规划求解技术
对地观测小卫星星座长期任务规划求解技术王海波;徐敏强;王日新;李玉庆【期刊名称】《系统工程与电子技术》【年(卷),期】2011(33)6【摘要】针对小卫星星座的成像特点和约束特性,建立长期任务规划数学模型.将该模型分解为初始轨道分配和冲突消解两阶段进行求解:首先将初始轨道分配问题映射为图的k-GCP模型,并提出了贪婪顶点序列着色算法进行分配;然后采用区间变量表示成像时间,根据区间变量间的时间关系对影响任务拓扑排序,设计了一种基于深度优先搜索的任务规划算法进行冲突消解.算例表明,该方法能够在满足时效性的前提下解决小卫星星座的长期任务规划问题.%In order to solve the long-term acquisition plan (LTAP) for small satelltes constellation, a mathematical model is constructed by analyzing the imaging characteristics and constraints of small satellites constellation. The model is divided into two sub-problems: initial orbit assignment and conflict resolution. First, initial orbit assignment is mapped into a κ-GCP model and a greedy vertex sequence coloring (GVSC) algorithm is proposed to assign orbit. For the conflict resolution phase, the impacted tasks are sorted based on their temporal intervals relations. A mission planning algorithm based on depth-first search is designed to tackle the second sub-problem. The experimental result shows the proposed approach is effective in solving the LTAP for small satellites constellation.【总页数】6页(P1293-1298)【作者】王海波;徐敏强;王日新;李玉庆【作者单位】哈尔滨工业大学深空探测基础研究中心,黑龙江哈尔滨150080;哈尔滨工业大学深空探测基础研究中心,黑龙江哈尔滨150080;哈尔滨工业大学深空探测基础研究中心,黑龙江哈尔滨150080;哈尔滨工业大学深空探测基础研究中心,黑龙江哈尔滨150080【正文语种】中文【中图分类】V474【相关文献】1.对地观测小卫星星座设计及区域覆盖性能分析 [J], 王启宇;袁建平;朱战霞2.“磁层-电离层-热层耦合”小卫星星座探测计划背景型号任务研究简介 [J], 刘勇;王赤;徐寄遥;李小玉3.小卫星、大星座,改变未来空间游戏规则——第三届小卫星技术交流会(2015)召开 [J], 贠敏4.用于对地观测和科学任务的小卫星 [J], Bartl.,R;李建华5.现代小卫星技术在对地观测中的应用 [J], 申家双;陈波;翟京生;凌勇因版权原因，仅展示原文概要，查看原文内容请购买。
时间选择性注意的认知神经机制
时间选择性注意的认知神经机制摘要：时间选择性注意是在时间知觉和选择性注意的基础上发展出来的研究领域之一，回顾了来自各种研究技术关于选择性注意认知神经机制的研究，并在此基础上对热点问题和发展趋势进行展望。
关键词：时间选择性注意时间知觉注意认知神经机制由于我们人类精力的有限性和世界信息的复杂性，我们需要对我们周围的信息有所选择的吸收，这就是选择性注意的功能。
从时间维度所做的研究才刚起步。
但是随着认知心理学和神经心理学2个领域的结合，时间选择性注意进一步加强了脑损伤患者以及脑疾病患者的研究。
另一方面，功能性脑成像技术应用于时间选择性注意的研究领域，也为理解人类时间选择性注意的脑机制提供了一条新的研究途径。
时间选择性注意探讨的就是如何利用时间维度的信息增加我们对事物认知的准确性，以及内在的认知和神经机制。
1.时间知觉与选择性注意1.1时间知觉与选择性注意的联系对时间选择性注意的研究巧妙地结合和借鉴了时间信息加工和选择性注意两方面的独立研究在我们的日常生活中，这两项功能都是人脑常见且不可或缺的功能。
时间知觉(time perception)在时间认知分段综合模型里属于极短时距(5s内)的研究范围。
时间知觉包括对事件持续性和顺序性的知觉。
目前从认知神经科学角度对时间知觉的研究仅限于事件持续性知觉。
选择性注意在我们适应环境的过程中起到举足轻重的作用。
大脑有限的加工能力和蜂拥而至的海量信息之间的矛盾，使我们必须有所选择，优先处理任务相关的信息，忽略或抑制无关信息的加工，从而更好地达到目的，越来越多的研究提示它们之间存在密切的联系。
1.2时间选择性注意注意调节能影响我们对刺激物呈现时间的估计。
分配给事件或活动的注意程度影响对事件或活动的时间估计。
被试同时执行两个交互任务时，对非时间任务的注意分配，会使被试对时间任务的时间判断正确率下降。
也有研究表明，在有限的认知能力前提下，如果非时间信息加工任务的难度越大，非时间信息处理就需要更多的认知能力，而时间处理所获得的信息量就减少，所知觉到的时间也越短。
提升视觉冲击力 Adobe Premiere Pro速度曲线调整方法
提升视觉冲击力：Adobe Premiere Pro速度曲线调整方法Title: Enhancing Visual Impact: Speed Curve Adjustment Techniques in Adobe Premiere ProIntroduction:Adobe Premiere Pro is a powerful video editing software widely used by professionals and multimedia enthusiasts for its extensive range of features and tools. One such feature that can significantly enhance the visual impact of your videos is the ability to adjust speed curves. In this tutorial, we will explore various techniques for manipulating speed curves in Adobe Premiere Pro, allowing you to create stunning visual effects.Section 1: Understanding Speed Curve AdjustmentTo start, it is important to understand what a speed curve is and how it affects the motion of your video footage. Speed curves control the rate at which a clip's speed changes over time, allowing you to apply smooth transitions or create dramatic effects. In Adobe Premiere Pro, the speed curve can be accessed through the Time Remapping feature.Section 2: Accessing Time RemappingTo access the Time Remapping feature, select the clip in your timeline and navigate to the "Effect Controls" panel. Expand the "Time Remapping" options and locate the stopwatch icon next to "Speed." Clicking on the stopwatch will activate keyframe recording for speed changes.Section 3: Adjusting Speed CurvesOnce you have activated keyframe recording, you can begin manipulating speed curves. To create a speed curve, simply click on the clip in the timeline at the desired point and adjust the speed value in the Effect Controls panel. The changes you make will create individual keyframes that can be adjusted further to achieve your desired effect.Section 4: Creating Smooth TransitionsOne common use of speed curve adjustment is to create smooth transitions, particularly during changes in pace or motion. To achieve this, add keyframes to control the clip's speed at the beginning and end of the transition. By dragging these keyframes, you can manipulate the speed curve to create a gradual acceleration or deceleration, resulting in a fluid transition.Section 5: Creating Dramatic EffectsIn addition to smooth transitions, speed curve adjustment can be used to create dramatic effects. For example, you can create a sudden speed ramp-up or ramp-down by placing keyframes closely together. This technique is often employed to emphasize action or add a sense of urgency to a clip. By experimenting with different placements and intervals of keyframes, you can achieve unique and impactful visual effects.Section 6: Fine-Tuning Speed AdjustmentsOnce you have established the general motion of your clip, it's time to fine-tune the speed adjustments. Adobe Premiere Pro offers several tools to help in this process. The "Bezier handles" enable you to customize the shape of the speed curve, allowing for more precise control over the acceleration or deceleration. Additionally, the "Temporal Interpolation" options providefurther flexibility, allowing you to choose from various interpolation methods such as linear, ease in, ease out, and more.Conclusion:By utilizing the speed curve adjustment techniques in Adobe Premiere Pro, you can significantly enhance the visual impact of your videos. Whether it's creating smooth transitions or adding dramatic effects, the ability to manipulate speed curves opens up endless possibilities for creative storytelling. With practice and experimentation, you can master this powerful feature and elevate your video editing skills to new heights.。
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PSYCHOPHYSIOLOGY
Vol. 28, No. 6
Copyright © 1991 by The Society for Psychophysiological Research, Inc.
See discussions, stats, and author profiles for this publication at: https:///publication/21338572
The Processing of Temporal Intervals Reflected by CNV-Like Brain Potentials
Printed in U.S.A.
The Processing of Temporal Intervals Reflected by CNV-Like Brain Potentials
THOMAS ELBERT', ROLF ULRICH^, BRIGITTE ROCKSTROH^, AND WERNER LUTZENBERGER^ 'Institutfur Experimentelle Audiologie, Universitdt MUnster, 'Psychologisches Institut, Eberhard-Karls-Universitdt, Tubingen, and ^Psychologisches Institut, Universitat Konstanz, Germany ABSTRACT The present study employed event-related potentials (ERPs) of the hrain to improve the understanding of temporal processing. A reproduction paradigm was realized by presenting a visual stimulus (illuminated screen) for intervals of varying length. A few seconds after presentation of such standard intervals the visual stimulus was switched on again and subjects were asked to reproduce the duration of the standard interval by turning off the illumination after a corresponding interval had elapsed. The length of standard intervals varied randomly with each of the following lengths being presented 20 times: 1, 2, 3, 4, 6, and 8 s. Reproduction was accurate for standard intervals up to 3 s but deteriorated with increasing interval length. Brain potentials during reproduction intervals of 1-3 s differed from those recorded during the longer intervals. A CNV-like slow negative shift developed during the shorter reproduction intervals. Negativity was reduced or even absent, when subjects had to reproduce standard intervals of 4 s or longer. The ERP results suggest that intervals shorter than 3-4 s may evoke a processing mode that is qualitatively different from the one dominating when periods in the range of several seconds have to be processed. DESCRIPTORS: CNV, Event-related potentials. Time perception.
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Some of the authors of this publication are also working on these related projects: Article Prevalence Of Violence-Related Traumatic Events And Symptoms Of Post-Traumatic Stress Disorder Among The Congolese Refugees In Uganda View project Motor Preparation and Processing View project All content following this page was uploaded by Thomas Elbert on 24 July 2014.
Article in Psychophysiology · December 1991
DOI: 10.1111/j.1469-8986.1991.tb01009.x · Source: PubMed
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