关于memory的课件
Unit 7 Memory (Period 7) 课件(共36张PPT)
If you want your brain to work well, you also need to relax. If you get too worried, your brain will slow down, and your memory will become less sharp.
Read the first paragraph and then answer the question.
Memory is very important. It helps you remember who you are, where you live, what you have learnt and what you plan to do in the future.
A Read the whole passage and then complete the table.
How to improve your memory
Exercise Do (1)_n_e_w__t_h_in__g_s__. your brain Change (2)_y_o_u_r__d_a_il_y_h__a_b_it_s__.
So, to improve your memory, you should exercise your brain, live a healthy life and stay relaxed.
MEMORY PPT课件.ppt
Strangers are just friends waiting to happen. Friends are the Bacon Bits in the Salad Bowl of Life.
Pass this on to all of your FRIENDS, even if it means sending it to the person that
A real friend is one who walks in when the rest of the world walks out
My father always used to say that when you die, if you've got five real friends, then you've had a great life.;
We all take different paths in life, but no matter where we go, we take a little of each other everywhere.;
Friends are God's way of taking care of us.
MEMORY
BARBRA STREISAND
Midnight Not a sound from the pavement Has the moon lost her memory
She is smiling alone In the lamplight
The withered leaves collect at my feet And the wind begins to moan
“海水呀，你说的是什么？” “是永恒的疑问。”
Unit7Memory复习课件牛津深圳版英语八年级上册
_u_n_l_e_s_s_y_o_u__s_t_arive there in time.
Unless it rains, the game will be played.
3．＝__I_f_it__d_o_e_s_n_'_t_r_a_i_n_， the game
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Unit 7 Memory
19．关闭；切断__s_w_i_tc_h__o_f_f 20．在某人的脑海中_i_n_o_n_e_'_s_m__i_n_d_ 21．远离_b_e__fa_r__(a_w__a_y_)_f_ro_m__ 22．在……的角落__a_t _t_h_e_c_o_r_n_e_r_o_f_…__
3.Please _d_o_n_'_t leave the office _u_n_t_il_ your friend comes back. 请不要离开办公室，直到你的朋友回来。
第 17 页
Unit 7 Memory
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注意事项： 主句部分只能使用动词will的一般将来时，不能使用be going to结构。
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Unit 7 Memory
13．一次_a_t_a__t_im__e_ 14．做某事有困难_h_a_v_e__tr_o_u_b_l_e_/d_i_f_fi_c_u_lt_y__d_o_in_g__s_th_.__ 15．和……相似__b_e_s_im__i_la_r__to_…_____ 16．练习做某事_p_r_a_c_ti_s_e_d_o_i_n_g_s_t_h_._ 17．想起__th_i_n_k__o_f…__ 18．添加……到…… _a_d_d_…__t_o_…__
谈论将来可能出现的情况时， quickly.
八年级英语上册 Unit 7 Memory课件 牛津深圳版
【7】unless conj. if ...not 除非 You can catch the bus unless you don’t get up early. 你
能赶上公共汽车，除非你不早起。 【应用】 ( C )You something easily unless you it.
【5】mind n. the part of a person that thinks, understands, imagines, and feels 头脑；大脑
v. be bothered by介意；pay close attention to 注 意
I’m trying to clear my mind of all this. 我正试图把这一 切都从我脑子里清理出去。
【9】step n. the way someone walks 步伐；one of a series of actions that you take in order to achieve something 步骤
If not, this should be your first step. 如果还没有，这就 是你要做的第一步。 【拓展】
二、根据汉语写出下列词组 1. (从银行财产中)提取(款) _ta_k_e__o_u_t________ 2. 涌出 _p_o_u_r_o_u_t________ 3. 做……有麻烦 _h_a_v_e_t_ro__u_b_le__d_o_in_g__ 4. 值…… _b_e_w__o_rt_h_._..______ 5. 均衡的饮食 a__b_a_la_n__c_e_d_d_i_e_t__ 6. 提高某人的记忆力 _im__p_ro__v_e_o_n_e_’_s_m__e_m_o_r_y___ 7. 水循环 _w_a_t_e_r_c_y_c_l_e_____ 8. ……的好方法 a__g_o_o_d__m_e_t_h_o_d_f_o_r_.._.
Memory课件1
you will remember it better. the simple future tense
We have already learnt to use conditional sentences to talk about probable results.
Look and say
If I’m hungry, eat some food I will______________.
1. If you do not get enough sleep every night, you will not remember things well. 2. Unless you get enough sleep every night, you will not remember things well. 3. You will forget something very quickly unless you understand it well. 4. You will be late for school if you do not leave now. 5. Unless you improve your handwriting, you will lose marks in the exam.
If I’m tired, have a rest I will_____________.
If I’m ill, I will see a doctor __________________.
If I’m late, I will say sorry _______________.
If it rains tomorrow, I_____________________. will watch TV at home If it _____________ doesn’t rain
英语PPTMemory
5
• If you say that something is, for example, the best, worst, or first thing of its kind in living memory, you are emphasizing that it is the only thing of that kind that people can remember.
• 4. Memory to follow the law, and timely review记忆要遵循规律，及时复习 • 5. Memory to have a good mental state 记忆要有良好的心理状态 • 6. Memory to a scientific method记忆要 有科学的方法
• • • • • 1.记性 2.回忆 3.内存 4.失忆 5.在人们记忆中最……的事情
And
• • • • some great films about memory 记忆memory is your ability to remember things.
Six ways to improve memory 的六种方法
提高记忆力
• 1.Memory should have a clear purpose 记忆要有明确的目的 • 2. Memory should have a strong interest记忆要有浓厚的兴趣 • 3. Memory to have a high degree of attention记忆要有高度的注意力
Seven kinds of food to improve memory 提高记忆力的七种食物
• • • • •
Cabbage, soy milk, fresh fish egg yolk
Unit 7 Memory (Period 2) 课件(共67张PPT)
Millie You will forget something very quickly unless you _u_n_d_e_rs_ta_n_d__it_w_e_ll_.
Unit 7 Memory
Reading
目录
1 Lead-in
Pre-Reading 2 3
Post-Reading 4
While-Reading
5 Review
Part I Lead-in
Getting ready
Look at the cartoon and answer the questions.
Part III While-Reading
Read the text and answer the questions
Memory Corner
Henry, Paula and Millie write for the school newspaper. They have written the short articles below to help students improve their memory.
Paula A good method for remembering the spelling of a word is to make a short sentence with each letter of the word. For example, if you want to remember how to spell the word “because”, you can use the sentence “Big
Unit 7 Memory (Period 4) 课件(共22张PPT)
supermarket.
If
, you will remember what things to buy.
• I don’t know what this word means.
If , you will find out its meaning.
• I hate getting up! I always feel tired in the morning.
Part III Review
Exercises
一、选择最佳答案填空。
(B)1. Peter _____ angry if you break his toy.
A. gets
B. will et
C. get
D. got
( )2. If you _____ salt into water, it _____. C A. put; disappears
A2 In pairs, make conversations about the sentences in A1 on page 103. Follow the example.
S1: What happens if you take a fish out of water? S2: It dies. S1: Are you sure? S2: Of course. I’m sure. If you take a fish out of water,
义句) __I_f___you _d_o_n_’t__ go to bed early, you will feel tired. 3. If you don’t improve your handwriting, you’ll lose marks in the exams. (改为同义句) m_U_a_rnk_lse_si_nsytohuei_em_xap_mr_o_sv_.eyour handwriting, you’ll lose
]memory 课件
![]memory 课件](https://img.taocdn.com/s3/m/4633b8fc770bf78a6529541a.png)
LISTENING PRACTICE
• This exercise will test your memory. Listen ,but do not take notes. After listening ,we will answer questions according to the tape.
5.method:
way of doing something
The best method of keeping slim is to exercise regularly.(有规律的）
True or false questions:
• 1. As you get older, your memory gets better. × • 2. Joyce’s article is about a man who lost his wife after an accident. × • 3. Making pictures in your mind helps you to remember things. √ • 4. Tony used a book to help him with his article. √ • 5. Our memory gets better if something bad happens to us. ×
Listening
• 5.What color were Grandma’s new glasses? Pink • 6.Where did the woman look for the glasses? In the kitchen • 7.Where did Grandma look for her In her bedroom glasses? • 8.Who looked all around the sittingroom? James
Unit 7 Memory (Period 5) 课件(共14张PPT)
Speaking
目录
Lead-in Post-Learning
1 2 While-Learning
3
Part I Lead-in
Show time
Talk about how to improve your memory.
Part II While-Learning
S2: Yes. You can make a short sentence with each letter of the word.
S1: Can you give me an example? S2: If you want to remember the word “family”, you can
Speak up
Do you have any special methods for remembering English words? Do they work? In pairs, talk about your experience. Follow the example.
S1: Do you have any special methods for remembering English words?
Thank you!
make the ve you”. S1: That’s a good idea.
S1: Do you have any special methods for remembering English words?
S2: Yes. You can ... S1: Can you give me an example? S2: If you want to remember the word ... S1: That’s a good idea.
Unit 7 Memory 课件11(牛津深圳版八年级上册)
11. letter 字母，信 There is a letter “h”in the world house. 在house 这个单词里有一个字母 h. I wrote a letter to him last night. 昨晚我写了一封信给他了。
12. worth 值得，有价值 Be worth doing 值得去做 This book is worth reading 这本书值得一看。 This city is worth _________(visit) visist n. 清单 Before I went shopping , I make a list of things I wanted to buy. 在我购物之前，我会列出一个要 买的东西的清单出来 name list 名单
短语: lose heart 失去信心 lose one’s life 丧生，死 lose one’s way 迷路 lose the game 输了一局
4. improve V. 改进，改善 We need to do something to improve our environment. 我们需要做点事情来改善环境。 Peter must _________his improve spelling. 彼得必须要改进他的拼写了。
9. silly adj. 可笑的 They're quite silly on this subject. 在这个问题上他们相当愚蠢。 同义词：stupid, foolish 反义词：clever, wise
10. mile 英里 英里约等于1.6公里 She lives just half a mile away. 她就住在半英里以外的地方。
Unit 7 Memory-沪教版初中英语二年级上册图文课件
exercise your brain, live a healthy life and stay relaxed ___________.
Read the first paragraph and then answer the question.
Memory is very important. It helps you remember
Thank You
Read the whole passage and then complete the table.
B What do you do to improve your memory? Do you have any good suggestions? Discuss these with your classmates.
What should we write down when we make notes?
Do we need to write complete sentences?
In what way are diagrams sometimes useful when making notes?
Read the passage. Then complete the diagram with the information from the passage.
Way to exercise your brain
Nancy usually took the No.46 bus to school. However, for a change she has decided to take another bus. It seems that she is arriving at school much faster than before.
Unit 7 Memory (Period 1) 课件(共51张PPT)
The little boy made his mother angry. 你使我成为世界上最幸福的人。
字母中间有一个”mile”。
(1) mile
n. 英里
常见的计量单位小结：
meter / metre 米
kilometer / kilometre 千米；公里
mile 英里 foot 英尺 inch 英寸 gram 克
kilogram 千克 pound 磅
她就住在半英里以外的地方。
She lives just half a mile away.
Unit 7 Memory
Vocabulary
目录
Words and
expressions 1
2
Notes
Part I Words and expressions
New words Getting ready
memory corner
n. 记忆力；记性；回忆；记忆 p.97 n. 角 p.97
(2) letter
n. 字母
在house 这个单词里有一个字母 h。
There is a letter “h”in the world house. 昨晚我写了一封信给他了。
I wrote a letter to him last night.
“Z”是英语字母表中的最后一个字母。
“Z” is the last letter in the English
Unit 7 Memory 词汇讲解 课件 2022-2023学年牛津深圳版英语八年级上册
•16. cycle n. 循环; 自行车
•The film is about the life cycle of butterflies. 这部电影是关于蝴蝶的生命周期。
•What about going for a cycle ride on Sunday? 我们星期天骑自行车去兜风如何？
17. similar adj.相似的 be similar to 与…相似 All big cities are quite similar. 所有的大城市都十分的相似。 Your idea is similar to mine. 你的观点和我的有点相似。
4. improve n. 改进，改善 (P98) (= make…better) improvement n.改进之处
We need to improve our environment. 我们需要改善环境。 Peter must improve his spelling. 彼得必须要改进他的拼写了。
13. trouble
trouble 不可数名词，前面可以用some, a lot of, any, no等来修饰。
have trouble (in) doing sth. 意为“做某事有困难”，其中，介词in可以省略.
同义词短语： have problems/difficulty doing sth 做某事有困难 have trouble /problems/difficulty with sth 在某方面有困难
Unit 7 Memory
1. Memory Corner (P99) memory n. 记忆力， 回忆 a memory for sth 对某事的记忆 memorize v (=remember) He has a good memory . 他有很好的记忆力。
八年级英语上册-Unit-7-Memory-Readingppt课件
• 4 Once we learn how to ride a bike, we will never forget how to do it. T / F
• B Before you read
• Look at the introduction, the title and the first sentence
• his study.
19
• 5. It is easier to remember these steps if you understand how the water cycle works.
• 如果你理解水循环是怎么工作的， 记忆这些步骤就会简单些。
• It 做形式主语，动词不定式to remember these steps 做真正
and fill in the blanks below.
30
• Henry To remember something
Imagine a (1)_ ict__u_r_e___: (2)
big , (3)__s_t _e_____, or (4)si__ll_y___ (e.g) “smile”:
我们应该找一个最好的方法去解决 这个数学问题。
imagine a picture 想象一幅图 in your mind 在你的脑海里
Please keep this word in your mind.请你把这个记在脑海里。
13
• 2. We can imagine there is a “mile” between the first letter and the last letter.
Unit 7 Memory
Reading
1
memory课件
AArtrhAturhtrhuurr
MEMORY Text analysis Reading in detail
Pancy
Joyooco e
MEMORY
Tony
Millie
Further understanding of the text
• After analyzing the text , let’s check how much you have remembered about it and at the same time we can also check your memory
fell down some stairs and landed
on my head.
Tom: Oh, I hope you don’t lose your
memory! How did the accident happen?
Ben: What accident?
5.method: way of doing something5.pig16. red rose
6.dog
17. beautiful flower
7.man
18. lady with an umbrella
8.girl with big eyes
19. fireworks
9.climbing boy
20. book
10.students at working
21. stars
MEMORY
There are twenty-one words and expressions all
together . They are:
1.pander
MEMORY介绍ppt课件
Foxconn Confidential
7
PCEBG YDC CT
内存大体经历的几个形式
从一有计算机开始，就有内存。内存发展到 今天也经历了很多次的技术改进，从最早的 DRAM一直到FPMDRAM、EDODRAM、SDRAM、 DDR-SDRAM、RDRAM、DDR2 SDRAM等，内存的 速度一直在提高且容量也在不断的增加。
Foxconn Confidential
26
PCEBG YDC CT
主频
内存主频和CPU主频一样，习惯上被用来表 示内存的速度，它代表着该内存所能达到的 最高工作频率。 内存主频是以MHz（兆赫）为单位来计量的。 内存主频越高在一定程度上代表着内存所能 达到的速度越快。内存主频决定着该内存最 高能在什么样的频率正常工作。
記憶體顆粒 核心工作時脈
DDR266 SDRAM
133MHz
DDR333 SDRAM
166MHz
DDR400 SDRAM
200MHz
理論傳輸頻寬 /資料寬度 2.1GB/Sec 64bit 2.7GB/Sec 64bit 3.2GB/Sec 64bit
DDR2-400 SDRAM
200MHz
DDR2-533 SDRAM
Foxconn Confidential
23
PCEBG YDC CT
DDR-II内存的其它一些改变包括电压下降为1.8v，因此 功率消耗、芯片温度和写入延迟不定性都得到了下降。 这也是因为带宽增加而内存延迟时间增加带来的结果。
尽管DDR-II内存采用的DRAM核心速度和DDR一样，我 们仍然要使用新主板才能搭配DDR-II内存，因为DDR-II 规格和DDR是不兼容的。首先DDR-II的针脚数量为240 针，而DDR内存为184针，接口不一样；此外，DDR-II 内存的VDIMM电压为1.8v，也和DDR内存的2.5到2.8v 不同。
memory
Journal of Information Science OnlineFirst, published on April 10, 2007 as doi:10.1177/0165551506076331We propose a new index structure called F-Tree to improve the performance of index operations in a flash memory database system. We present the notion of compressed index rewriting to han-dle slow write/erase operations.data access due to system faults such as power failure. The well known index structure for a memory-based system is T-Tree [8]. T-Tree has the characteristics of the AVL-Tree, which has O(logN) tree tra-verse. T-Tree also has the characteristics of B-Tree, which has many entries in a node for space efficiency. T-Tree is considered a good structure for a memory-based index in terms of operation per-formance and space efficiency [10]. However, in [11], the performance of the B-Tree could outperform that of the T-Tree due to the concurrency control overhead. Thus, for performance reasons, a mem-ory-based system generally uses enhanced B-Trees as well as T-Trees.In disk-based systems, each node block may contain a large number of keys. The number of sub-trees in each node, then, may also be large. The B-Tree is designed to branch out in this large num-ber of directions and to contain a lot of keys in each node so that the height of the tree is relatively small. This means that only a small number of nodes must be read from the disk to retrieve an item. The goal is to have quick access to the data, and this means reading a very small number of records [12]. That is, the depth of the tree is very important because the number of node access refers to the number of disk I/O in the course of the tree traverse to search for or insert a node. Thus, the disk-based system minimizes the disk I/O cost by using a shallow and broad tree index. The memory-based system, on the other hand, does not prefer a shallow and broad tree index. This is because the depth of the tree or the size of the tree node can be adjusted to improve index performance, and the node access cost is very low in fast RAM.Unfortunately, index design and the implementation of a disk-based or memory-based system could not be applied directly to a flash memory-based system. This is due to the following draw-backs of flash memory. First, flash memory cannot be overwritten unless it is erased first. Note that writes and erases over flash memory take 20 and 200 times more than reads, respectively [13]. Thus, the write and erase operations should be handled differently from the read operation in terms of the execution cost. Second, the frequent erasing of some particular locations of the flash memory could quickly deteriorate the overall lifetime of the flash memory because each erasable unit has a limited cycle count on the erase operation. This requires the index management module to wear down all memory blocks as evenly as possible. Third, the write operation consumes nine times more energy than the read operation in portable devices, which have small batteries [10]. For these reasons, any direct application of the traditional index implementation to flash memory could result in severe performance degradation, and could significantly reduce its reliability.In order to improve the index operation performance of B-Tree in flash memory storage devices, B-Tree Flash Translation Layer (BFTL) [14] was proposed. BFTL could efficiently handle fine-grained updates caused by B-Tree index access and reduce the number of redundant write opera-tions in flash memory. The implementation of BFTL was done directly over the flash translation layer (FTL) so that no modifications to the existing application systems were needed. BFTL sits between the application layer and the flash memory block-device emulated by FTL.As shown in Figure 2, BFTL consists of a small reservation buffer and a node translation table. When the applications insert or delete records, the newly generated records are temporarily held by the reservation buffer to reduce redundant writes. Since the reservation buffer only holds an ade-quate amount of records, the index unit of the records should be timely committed (flushed) to the flash memory. The node translation table maintains the logical sector addresses of the index units of the B-Tree node so that the collection of the index units can be more efficient by smartly packing them into few sectors. Although BFTL achieves an enhanced performance in terms of write opera-tions, it requires an additional hardware implementation of the reservation buffer and the node translation table. Furthermore, the search overhead can increase with frequent access to the reser-vation buffer and the node translation table.Both BFTL and our scheme aim to improve index operation performances for flash memory stor-age devices. However, the focus of our scheme is different from that of BFTL, which aims to mini-mize the number of redundant write operations in B-Tree. In other words, our scheme aims to reuse tree nodes by index compression and node rewriting techniques in B+-Tree, which is an enhanced index of B-Tree. Our scheme sits between BFTL and FTL because it can compress and rewrite the packed index unit of BFTL. Therefore, our scheme and BFTL can be merged to maximize perform-ance synergy in flash memory storage systems.B-Tree-Related Applications Other ApplicationsNode TranslationTableThe CommitBFILPolicyReservation BufferFlash Memory Translation Layer (FIL)Flash Memory+-Tree.nodes within some pre-defined range. As data is inserted or removed from the data structure, the number of child nodes varies within a node, and so the internal nodes are coalesced or split so as to maintain the designed range. Because a range of child nodes is permitted, B+-Trees do not need re-balancing as frequently as other self-balancing binary search trees, but may waste some space since the nodes are not entirely full. The lower and upper bounds on the number of child nodes are typically fixed for a particular implementation [15]. The B+-Tree is kept balanced by requiring that all leaf nodes have the same depth. This depth will increase slowly as elements are added to the tree, but an increase in the overall depth is infrequent, resulting in all leaf nodes being one more hop further removed from the root. By maximizing the number of child nodes within each internal node, the height of the tree decreases, balancing occurs less often, and efficiency increases. In [8], the simulation shows that the average fill factor of 69% is the optimal value in a B+-Tree node. That is, saving too many entries in a node could lead to performance degradation due to frequent insert/delete operations caused by tree re-balancing.However, direct B+-Tree implementation on flash memory could lead to performance degradation due to slow write operations. Furthermore, this implementation could lead to system unreliability due to frequent write operations in the same location [5, 16]. Therefore, in order to implement the B+-Tree in flash memory, one of the most important goals is to reduce the number of write and erase operations. To achieve this goal, we propose a compressed index rewriting scheme that exploits sep-arated field compression and one-way rewrite techniques.As mentioned above, flash memory should perform erase operations prior to actual write opera-tions. Since erase operations set every bit to 1 to initialize each block, write operations are allowed to change individual bits from 1 to 0 in a one-way fashion. That is, in order to change from 0 to 1, another erase operation should be performed prior to the actual change. However, in the case of changing a cer-tain value from 1 to 0, flash memory could perform the rewrite operation without the erase operation [17]. If we exploit this special feature of a one-way rewrite, we could reduce the overhead of the write operation and enhance both the indexing performance and the lifetime of flash memory.The one-way rewriting technique is able to write the same node at least twice. This is achieved by compressing the original node prior to the first write operation. We achieved a 52% compression ratio by using reordered field compression. Since the compressed data area is sequentially allocated one by one, the rest of the 52% area of the original node can be reserved for another write opera-tion. If the second write operation is requested, the first half of the node is invalidated and the com-pressed data of the second one is sequentially allocated.Unfortunately, if the size of the contents obtained from the compression is larger than half of the original size, we do not exploit the one-way rewriting technique. However, we can avoid most of these cases by properly handling the level of compression algorithm. We propose an enhanced B+-Tree index called F-Tree, which exploits one-way rewriting and a reordered field compression. The internal and leaf node structures of the F-Tree index are illustrated in Figure 4.We used the LZO [18] algorithm for the node compression because LZO is not only simple but also easy for handling source codes. As shown in Table 2 [19], the LZO compression speed is about 4 MB/s and the decompression speed is about 15 MB/s in a Pentium 133MHz CPU. We can control the compression ratio and speed by varying the compression level of the LZO algorithm.We used the LZO-3level in Table 2 and slightly enhanced the node compression ratio by regroup-ing the key and pointer fields in a similar sequence. Our simulation showed that the compression ratio is 55.6% and 54.7% for the internal node and the leaf node, respectively. These compression ratios enable the one-way rewriting module to rewrite the original node after the first write opera-tion in the compression mode. If F-Tree exploits a more efficient compression algorithm than LZO, the index operation performance can be much more enhanced.Since CPU and RAM are far faster than flash memory access, the compression and decompres-sion overhead is negligible in our experiments. This is because the main performance factor is at a slow erase/write operation speed in flash memory, not at a read speed in CPU and RAM. In F-Tree, the main reason for node compression is to reduce slow erase/write operations by a one-way rewrit-ing procedure, and to contain more entries (keys and pointers) in the node. For I/O performance in F-Tree, the physical page size of flash memory corresponds to the size of one node. That is, one pageIn order to compress the leaf or internal nodes efficiently, FM_Write() separates the node entries into a key array and a pointer array and then calculates the key offset and the pointer offset, after which it compresses the array of differences between the original value and the offset. If the size of the contents obtained from the difference compression is smaller than half of the original size, it writes the compressed contents to the first half of the original node and reserves the second half, which is set to ‘1’, for the second write operation. If the second write operation is requested the next time, FTM invalidates the first half of the compressed node and rewrites the compressed contents in the second half.The detailed procedure of handling index operations can be shown in a pseudo-code form as Algorithm 1.Algorithm 1. Handling index operations for flash memoryint FM-Write(Node *N) // write data in flash memory and return compress mode{switch (Type(N)) {// check node typecase ROOT_NODE: // root node is not compressed.N. isCompressed←false;flash_memory_erase_operation(N);flash_memory_write_operation(N);return NOT_COMPRESSED;case LEAF_NODE: // leaf nodes or internal nodes can be compressed.case INTENAL_NODE:break;} // end of switch// compress key and pointerCreate a temp node T in RAM;key_offset←Minimum(N.K[1..n]); // find key offsetpointer_offset←Minimum(N.P[1..n]); // find pointer offsetT←LZO_compress_key(N, key_offset); // compress (Ki – key_offset)arrayT←T+ LZO_compress_pointer(N, pointer_offset);// compress (Pi – pointer_offset)arrayif ( SizeOf(T) >⎡SizeOf(N)/2⎤) {// check compressed size.N. isCompressed←false; // write non-compressed dataflash_memory_erase_operation(N);flash_memory_write_operation(N);return NOT_COMPRESSED;}// write compressed dataif ((first half is free) or (second half is full) ){// do first write: compress and write first half.N←T+ fill_second_half(1);// fill second half with 1 to rewrite second halfN. isCompressed←true;flash_memory_erase_operation(N);flash_memory_write_operation(N);return COMPRESSED_FIRST;}else {// second half is free//do second_write: compress and rewrite second half.N←fisrt_half+ T; // rewrite second halfN. isCompressed←true;flash_memory_write_operation(N); // just rewrite without erase operation.return COMPRESSED_SECOND;}} // End of FunctionNode *FM-Read(Node *N) // read data in flash memory{N←flash_memory_read_operation();switch (Type(N)) {// check node typecase ROOT_NODE: // root node is not compressed.return N;case LEAF_NODE: // leaf nodes or internal nodes may be compressed.case INTENAL_NODE:if ( N.isCompressed= false)return N;break;default:return NULL;// read error.} // end of switch.// uncompress entry(Ki ,Pi ).Create a temp node T in RAM;T.K[1..n]←LZO_uncompress_key(N); // uncompress key arrayT.P[1..n]←LZO_uncompress_pointer(N);// uncompress pointer array return T;} // End of FunctionNode*FT-Search (int key){R←block containing root node of tree;N←FM-Read(R); // read R in flash memorywhile ( Type(N) ¹ LEAF_NODE) { // N is not a leaf node of tree.q←number of tree pointers in node N ;if ( key≤N.K1) // N.Kirefers to the i th search field value in node N.N←N.P1 // N.Pirefers to the i th tree pointer in node N.// N is first child node.else if ( key> N.Kq-1)N←N.Pq // N is last child node.else {Search node N for an entry i such that N.Ki-1 <key≤N.Ki;N←N.Pi}N←FM-Read(N); }// end of while loopSearch node N for entry (Ki ,Pi) with key= Ki; // search leaf node N.if( entry_found ){N←N.Pireturn FM-Read(N) // read data record.}else {print_error ( “record with search field value key is not in the data file” );return NULL;}} // End of FunctionBoolean FT-Insert (int key, record*rec){R←block containing root node of tree; N←FM-Read(R);while ( Type(N) ≠LEAF_NODE) { // N is not a leaf node of tree.q←number of tree pointers in node N ;if ( key≤N.K1) N←N.P1else if ( key> N.Kq-1) N←N.Pqelse { Search node N for an entry i such that N.Ki-1 <key≤N.Ki; N←N.Pi}N←FM-Read(N); }// end of while loopSearch node N for entry(Ki ,Pi) with key= Ki; // search leaf node N.if(entry_found)return false; // record already in file, cannot insert.else {// insert entry in the tree to point to record.Create entry(K,Pr)where Pr points to the new record rec;if ( leaf node N is not full) {insert entry(K,Pr)in correct position in leaf node N;FM-Write(N);}else { // split if leaf node is fullCopy N to Temp // Temp is an oversize leaf node to hold extra entry.Insert entry(K,Pr)in Temp in correct position; // Temp now holds (Pleaf + 1) entries in RAM.New←Create a new empty leaf node for the tree;New.Pnext ←N.Pnext;J←é (Pleaf + 1)/2ù;N? First J entries in Temp;N.Pnext ←New;New←Remaining entries in Temp;Insert the leaf node New and key in correct position in parent internal node;FM-Write(N);FM-Write(New);// if parent is full, split it and propagate the split further up.}return true;} // end of else} // End of FunctionBoolean FM-Delete (int key){R←block containing root node of tree; N←FM-Read(R);while ( Type(N) ≠LEAF_NODE) { // N is not a leaf node of tree.q←number of tree pointers in node N ;if ( key≤N.K1) N←N.P1else if ( key>N.Kq-1) N←N.Pqelse { Search node N for an entry i such that N.Ki-1 <key≤N.Ki; N←N.Pi}N←FM-Read(N); }// end of while loopSearch node N for entry(Ki ,Pi) with key= Ki; // search leaf node N.if(! entry_found)return false; // key is not in tree, cannot delete. else {// delete entry and record.Remove entry (Ki ,Pi) in node N;FM-Write(N);Remove Record which Pi points to;FM-Write(Record);Decrease number of tree pointers in node N ;// underflow: if number of tree pointers is less than predefined minimum factor.if ( ! is_underflow(N) )return true;// handle underflow.if (Type(N) = ROOT_NODE) {Collapse N ;Make the remaining child the new root ; // so tree height decreases.FM-Write(N);}else { // merge immediate neighbor nodesL←number of entries in left node ;R←number of entries in right node ;if ( L> minimum_size&& R > minimum_size ) // minimum number of entries in a node return true;else { //either L or R is less than minimum_size in nodeBalance current node: // since the node has too few entries due to the removalInsert all the key values in the two nodes into a single node S;FM-Write(S);Merge with the neighbor whose pointer is the current node’s parent;FM-Write(N);// Continue merging the internal nodes until you reach a node with the correct size or the root node;}} // end of mergereturn true;} // end of else} // End of Function4.Performance evaluationWe compared the performance of F-Tree to the well known index scheme, B+-Tree, by means of com-puter simulation. Alternative approaches might include: (1) measurements from an actual imple-mentation, or (2) the use of approximate analytic methods. With regard to the first approach, even assuming that the obstacle resulting from a large programming effort to implement the whole usable system could be surmounted, there remains a problem with consistent measurement. This is because there are several interference factors such as kernel interrupt handling, context switching, paging, cleaning, garbage collecting, caching, prefetching, and buffering. These factors lead to unpredictable time delays and incorrect results in a real system.If an accurate and robust model is constructed in the analytic approach, it is much easier to eval-uate the performance in comparison with a simulation approach in terms of the required program-ming endeavour and the computing resources. However, constructing an accurate analytic model is not easy because it possesses a complex and dynamic run time nature, which is hard to model with clear mathematical expressions. Although all the detailed factors for the run time nature are included in the analytical model, usually a simulation study or an actual measurement needs to be performed in order to validate the performance evaluation results of an analytic model.4.1.Simulation setupWe compared the performance of the F-Tree index with two types of the B+-Tree index. The average fill factor of the F-Tree was fixed at 69%, which is a general value for the best performance [8]. We denote this F-Tree as FTR69. On the other hand, we divided the average fill factor of B+-Tree intoQueuing system model for simulation.[3]K. Yim, A novel memory hierarchy for flash memory based storage systems, Journal of SemiconductorTechnology and Science5(4) (2005) 262–9.[4] C. Park, J. Seo, D. Seo, S. Kim and B. Kim, Cost-efficient memory architecture design of NAND flash mem-ory embedded systems. In: Proceedings of the21st International Conference on Computer Design, San Jose, California,13–15 October 2004(IEEE Computer Society, 2004) 474–9.[5] C. Wu, L. Chang and T. Kuo, An efficient R-Tree implementation over flash-memory storage systems. In:E. Hoel and P. Rigaux (eds),Proceedings of the ACM GIS03, New Orleans, Louisiana, 2003(ACM, NewYork, 2003)17–24.[6]H. Kim and S. Lee, A new flash memory management for flash storage system. In:Proceedings of the 23rdAnnual International Computer Software and Applications Conference,Phoenix, Arizona, 1999(IEEE Computer Society, 1999) 284–9.[7]S.K. Cha, J.H. Park, and B.D. Park, Xmas: an extensible main-memory storage system. In: F. Golshani andK. Makki (eds), Proceedings of the 6th ACM International Conference on Information and Knowledge Management,10–14 November 1997(ACM, New York, 1997) 356–62.[8]R. Elmasri and S.B. Navathe, Fundamentals of Database Systems(Addison-Wesley, 1994).[9]N. Beckmann, H.P. Kriegel, R. Schneider and B. Seeger, The R*Tree: an efficient and robust access methodfor points and rectangles. In: H. Garcia-Molina and H.V. Jagadish (eds), Proceedings of the ACM SIGMOD International Symposium on the Management of Data, 23– 25May 1990(ACM, New York, 1990) 322–31.[10] C. Lee, K. Ahn and B. Hong, A study of performance decision factor for moving object database in mainmemory index. In: Y. Eom (ed.)Proceedings of the Korea Information Processing Society 2003 Spring Conference, Seoul10–11 May(KIPS, Seoul, 2003) 1575– 8.[11]H. Lu, Y. Yeung Ng and Z. Tang, T-Tree or B-Tree: main memory database index structure revisited. In:Proceedings of the 11th Australasian Database Conference,31 January–3 February 2000(IEEE Computer Society, 2000).[12]Software Design Using C++(2006). Available at: /carlsond/swdesign/btree/btree.html (accessed 5 February 2006).[13]What is Flash?(2006) Available at: /Products/Semiconductor/Flash/WhatisFlash/FlashStructure.htm (accessed 11 July 2006).[14] C. Wu, L. Chang and T. Kuo, An efficient B-Tree layer for flash-memory storage systems.In: J Chen andS.S. Hong (eds), Proceedings of the RTCSA, Tainan, Taiwan, 18–20 February 2003(Springer, Berlin/ Heidelberg, 2003) 409–30. [Springer, Lecture Notes in Computer Science, 2968/2004.][15]B-tree (2006). Available at: /wiki/B-tree (accessed 5 February 2006).[16]J. Nam and D. Park, The efficient design and implementation of the B-Tree on flash memory. In: M.H. Kim(ed.)Proceedings of the 32nd Korea Information Science Society Fall Conference, Seoul, 11–12 November, 2005(KISS, Seoul, 2005) 55–7.[17]J. Jeong, S. Noh, S. Min and Y. Cho, A design and implementation of flash memory simulator, Journal ofKorean Information Science: C 8(1) (2002) 36–45.[18]LZO (2006). Available at: /opensource/lzo/#download (accessed 5 February 2006).[19]LZO (2006). Available at: /opensource/lzo/lzodoc.php (accessed 5 February 2007)[20]H. Schwetman, CSIM User’s Guide for Use with CSIM Revision 16(Microelectronics and ComputerTechnology Corporation, Austin, 1992).[21]K. Yim and K. Koh, A study on flash memory based storage systems depending on design techniques. In:Proceedings of the 30th Korea Information Science Society Fall Conference, Seoul, 21–22 October, 2003 (KISS, Seoul, 2003) 274–6.。
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1.pay attention to 注意 2. go wrong 出毛病，出错 出毛病， 3. break down 抛锚 4. for example 例如 5. the Guinness Book of Records 吉尼斯世界记 录大全 6. a short-term/long-term memory 长/短时记 短时记 忆 7. lose memory 失忆 8. become worse 变得更糟 9. a man with an injured brain 一个脑伤的男人
Conditional clauses with if and unless 含有if的复合句由两个分句组成； 为连词， 含有 的复合句由两个分句组成；if 为连词，引 的复合句由两个分句组成 导条件状语从句，另一句为主句。 导条件状语从句，另一句为主句。 如果谈论的是某一个动作发生后势必会产生某个 结果，那么主从句都用一般现在时态。 结果，那么主从句都用一般现在时态。 e.g. If you boil water, it becomes steam. If you drop a glass, it breaks. If you heat metal, it melts. If you run, you sweat. If you put wood into water, it floats __________ (float).
11. end v. & n. 结束 以…为结尾 结束/以 为结尾 e.g. Their quarrel ended with a peaceful talk. /The war came to an end. /In the end, they stopped arguing. /There will be a contest at the end of this month./The bank is at the end of this street./He was anxious to know the ending of the story(结局） 结局） 结局 12. cost v. & n. 花费 e.g. The antique cost him thousands of dollars./The cost of Obama’s inauguration was about $150 million.
Chapter One Memory
Presentation Reading Vocabulary Language Practice speaking
short term memory 短时记忆 long-term memory 长期记忆 include 包含，包括 包含， feature 特征，特色， 特征，特色， 要素，（报纸的） ，（报纸的 要素，（报纸的）特 写 topic 论题，题目 论题，
death 死亡 2. memorize 记住 3. the Guinness Book of Records 吉尼斯记录大全 4. be connected to 与…相连 相连 5. hear about 听说 6. dramatic 戏剧性的 7. probably 很可能，大概，或许 很可能，大概， 8. president 总统 9. spider 蜘蛛 10. for example 例如 11. amazing 令人惊叹的 了不起的 令人惊叹的/了不起的
条件句放句首，从句后面要加逗号， ●若 if 条件句放句首，从句后面要加逗号，和主句 隔开。 隔开。 用法相似，相当于if…not ● unless 与if 用法相似，相当于 e.g. You will fail the exam if you don’t prepare for it.→ You will fail the exam unless you prepare for it. If he doesn’t look up the word in the dictionary, he won’t know its meaning. → He won’t know the word’s meaning unless he looks it up in the dictionary. gets She will miss the train unless she _______ up early.
如果谈论的是‘如果’ 如果谈论的是‘如果’某一个动作或事情发生 很可能将会产生某种结果， 后，很可能将会产生某种结果，那么在复句中主 句的动词用一般将来时， 句的动词用一般将来时，而if从句仍然是一般 从句仍然是一般 现在时。 现在时。 e.g. If it rains, we won’t take a hike tomorrow. He will get up school on time if the clock goes off. If he arrives in Hong Kong, he will call me. If you don’t start early, will miss you _________the beginning of the film (miss)
mind v. 介意做某事 e.g. Would you mind passing me some tissues? 4. sensible adj. 明智的 (adv. sensibly) e.g. I don’t think his choice is sensible./Cathy dealt with the problem most sensibly of all. 5. topic n. 主题，话题 主题， e.g. The topic of this activity is how to protect our environment. /She wrote some essays on this topic.
1. memory n.记忆，记忆力 记忆， 记忆 e.g. People have a long-term and a short-term memory. /Grandma has a bad memory. 2. article n.文章 文章 e.g. He wrote articles for the Saturday Review. 3. mind n. 大脑，头脑，想法，思维 大脑，头脑，想法， e.g. has a very open mind./Have you made up your mind to leave?/Justin has changed his mind. （下决心 改变注意） 下决心/改变注意 改变注意）
13. amazed/amazing adj. (感到惊叹的 令人吃 感到惊叹的/令人吃 感到惊叹的 惊的） 惊的）amaze v. 使人惊讶 e.g. Michael Fred Phelps is really amazing. He has won 14 Olympic gold medals so far. His excellent performance at Beijing Olympics amazed the whole world. But recently, we feel quite amazed at the news of his smoking marijuana(大 大 麻）! / mæri’hwa:nə/ 14. vehicle 车辆 e.g. During the rush hour, streets are always flooded with vehicles.
8. memorize v. 记住，熟记 (memory) 记住， e.g. He could memorize all names of the novels written by Charles Dickens. 9. dramatic adj. 戏剧性的，令人印象深刻的，激 戏剧性的，令人印象深刻的， 动人心的 (n. drama ) e.g. His dramatic experiences in Africa made all of us interested. 10. death n. 死亡 (v. die/ dead adj.) e.g. The death of the famous actress shocked the world./We found the dog dead in a cave./The patient was dying.
11. 12. 13. 14. 15. 16.
be connected to 与…相连 相连 a large spider 一只大蜘蛛 be/feel amazed at …对…感到惊讶 对 感到惊讶 make an excuse 找借口 借故 找借口/借故 make an apology to sb. 道歉 write an article on the topic 写一篇关于 这个主题的文章 17. include a feature about sth. 增加一个关 于…的特写（报道） 的特写（报道） 的特写 18. look up a word in the dictionary 在字典 里查询单词
6. injured adj. 受伤的 (v. injure n. injury) e.g. The news report says about 20 people were injured in the bus accident. The accident injured his brain. (事故伤害 事故伤害 了他的大脑）。 了他的大脑）。 7. imagine v. 想像 (n. imagination) e.g. I can’t imagine what will happen to our life in the not distant future. Use your imagination to make up a good story. 用你的想像力来编一个好故事。 用你的想像力来编一个好故事。