Pre-class Test 4
新概念英语Pre-UNIT4答案
新概念英语Pre-UNIT4答案1、If you know the answer, _______ your hand, please. [单选题] *A. put up(正确答案)B. put downC. put onD. put in2、38．These workers ___________ this bridge since one year ago. [单选题] * A．buildB．are buildingC．have built (正确答案)D．built3、She was seen _____ that theatre just now. [单选题] *A. enteredB. enterC. to enter(正确答案)D. to be entering4、25．A watch is important in our life. It is used for ______ the time. [单选题] * A．telling (正确答案)B．sayingC．speakingD．holding5、32．There are about __________ women doctors in this hospital. [单选题] * A．two hundred ofB．two hundreds ofC．two hundredsD．two hundred (正确答案)6、Let us put the matter to the vote,（）? [单选题] *A. will youB. can weC. may ID. shall we(正确答案)7、If it _______ tomorrow, I won’t go there. [单选题] *A. rains(正确答案)B. is rainingC. will rainD. would rain8、____ is standing at the corner of the street. [单选题] *A. A policeB. The policeC. PoliceD. A policeman(正确答案)9、Tony is a quiet student, _______ he is active in class. [单选题] *A. soB. andC. but(正确答案)D. or10、How _______ it rained yesterday! We had to cancel(取消) our football match. [单选题] *A. heavily(正确答案)B. lightC. lightlyD. heavy11、_____ the project, we'll have to work two more weeks. [单选题] *A. CompletingB. CompleteC. Having completedD.To complete(正确答案)12、As for the quality of this model of color TV sets, the ones made in Chine are by no means _____ those imported. [单选题] *A inferior thanB less inferior toC less inferior thanD. inferior to(正确答案)13、_______ hard, _______ you’ll fail in the exam. [单选题] *A. Studying; forB. Study; or(正确答案)C. To study; andD. Study; and14、Grandfather lives with us. We all _______ him when he gets ill. [单选题] *A. look after(正确答案)B. look atC. look forD. look like15、20．Sometimes it often rains ________ in my hometown in summer. [单选题] * A．heavyB．hardlyC．heavily(正确答案)D．strongly16、The reason why I didn't attend the lecture was simply（）I got a bad cold that day. [单选题] *A. becauseB. asC. that(正确答案)D. for17、26．—Mary, is this your pen?—No, it isn't. ________ is black. [单选题] *A．MyB．IC．MeD．Mine(正确答案)18、( )Keep quiet, please. It’s ________ noisy here. [单选题] *A. many tooB. too manyC. too muchD. much too(正确答案)19、My sister gave me a _______ at my birthday party. [单选题] *A. parentB. peaceC. patientD. present(正确答案)20、I like booking tickets online，because it is _______. [单选题] *A. boringB. confidentC. convenient(正确答案)D. expensive21、I have worked all day. I'm so tired that I need _____ . [单选题] *A. a night restB. rest of nightC. a night's rest(正确答案)D. a rest of night22、No writer will be considered（）of the name until he writes a work. [单选题] *A. worthlessB. worthy(正确答案)C. worthwhileD. worth23、What’s the point of going to school when I can’t do anything there? [单选题] *A. 时间B. 意义(正确答案)C. 方向D. 目标24、There may be something wrong with her _______. She can’t see things clearly. [单选题] *A. eyes(正确答案)B. earsC. mouthD. nose25、--Do you have a _______?--Yes, I _______ at a clothes store. [单选题] *A. work; workB. work; jobC. job; jobD. job; work(正确答案)26、The manager isn’t in at the moment. May I _______ a message? [单选题] *A. take(正确答案)B. makeC. haveD. keep27、I_____you that I had made the right decision. [单选题] *A.ensuredB.insuredC.assured(正确答案)D.for sure28、pencil - box is beautiful. But ____ is more beautiful than ____. [单选题] *A. Tom's; my; heB. Tom's; mine; his(正确答案)C. Tom's; mine; himD. Tom's; my; his29、Mary _____ be in Paris. I saw her just now on campus. [单选题] *A. mustn'tB. can't(正确答案)C. need notD. may not30、The manager gave one of the salesgirls an accusing look for her（）attitude towards customers. [单选题] *A. impartialB. mildC. hostile(正确答案)D. opposing。
test bench 教程
最近项目上要用到FPGA，之前用的一直是verilog，后面换成了VHDL。
对ISE一窍不通啊，研究了一些testbench文件的编写，record一下。
借用一下博文/lovelink/item/ff34ce9b12f45988581461ac的话。
首先对TESTBENCH作一个形象一些的比喻吧，它就象是一个面包板（做过电路实验吧），他对外没有任何接口，但它要向要插在他上面的器件提供接口，这样才能正确的插入，还有它必须对插在它上面的器件提供正常的信号。
当然在它上面还必须要有这个器件。
这时就完成了一个TESTBENCH。
应该大概明白了其中的意思了吧。
好了，根据上面的比喻我们可以非常明确的知道一个TESTBENCH要写一些什么东西，首先它对外无接口，所以它的实体部分是空的。
在它上面要有相应的器件，所以在它的结构体中要申明我们要测试的器件，也就是component的申明。
还有就是它要对器件提供接口，所以它的结构体应该提供一些信号，并且要对这些信号进行正确的测试赋值。
当然还要进行一些插入工作，就是信号的对应工作。
这样一个TESTBENCH就完成了。
原理很简单的，应该很容易明白。
不过在真正的测试中可能不会用太多的这种方式吧，应该会选用测试向量吧，这个的准确性更高一些。
不过怎么样写测试向量，这到是一个有大学问的东西，因为当我们的管脚很多的时候，测试的向量数目是要心指数增长的，当然不可能把所有的情况都测试完成了，只有是测试其中的一部分，这儿怎么样写出有代表性的一组测试向量是很有学问的，应该说是研究的热点吧。
几个testbench要用到的重要语句：（1）wait：无限等待，表示永远挂起，对于汉语wait语句的进程来说，进程在一开始执行一次后面就不执行了；（2）wait on 信号表：敏感信号等待语句，等待敏感信号表中的信号发生变化才执行；（3）wait until 表达式：条件等待语句，当条件表达式中所含的信号发生了变化，并为true时，进程才脱离等待状态；（4）wait for 时间表达式：此语句中声明了一个时间段，从从执行到当前的wait语句开始，只要这个时间段内，进程处于等待状态，超过这段时间，进程自动恢复执行该等待语句的下一条语句。
新模式英语1第三版课件PreUnitWelcometoOurClass
LESSON
B Complete the chart about your class.
Teacher’s name Number of students Number of hours
Miss White 40
4 hours every week
LESSON
C Listen and practice saying the numbers from 0 to 20.
1. Frank: ____G__o_o_d_m__o_rn__in_g______. Welcome to our class. Student: Hello. Thank you.
2. Grace: Hi!______H_o_w__a_re__y_o_u________？ Darcy: Fine, thanks. ______H__o_w__a_re__y_o_u_______？
LESSON
F Read about Gina and Clara.
Name: Gina Smith Address: 14 Second Street Phone: 130 4789 ××××
Name: Clara Black Address: 15 Redhill Road Phone: 8418××××
You
Your partner
____________ ____________
____________ ____________
____________ ____________
LESSON
address /əˈdres, 美 ˈædres/ n. 地址 chart /tʃɑːt/ n. 图表 circle /ˈsɜːkəl/ v. 在……上画圈；将……圈起来 information /ˌɪnfəˈmeɪʃən/ n. 信息 number /ˈnʌmbə/ n. 数字 phone /fəʊn/ n. 电话 say /seɪ/ v. 说，讲
class操作评估标准
class操作评估标准
1. 准确率（Accuracy）：准确率是分类正确的样本数占总样本数的比例。
它衡量了模型对所有类别的分类能力。
2. 精确率（Precision）：精确率是指模型在预测为正例的样本中，真正例的比例。
它衡量了模型对正例的判断准确性。
3. 召回率（Recall）：召回率是指模型成功预测为正例的样本占实际正例的比例。
它衡量了模型对正例的识别能力。
4. F1值（F1-score）：F1值是精确率和召回率的调和平均值，综合考虑了模型的准确性和识别能力。
5. 特定类别的评估指标（Specific Class Evaluation Metrics）：针对多类别分类问题，可以针对每个类别计算准确率、精确率、召回率等指标，以更细粒度地评估模型在不同类别上的表现。
6. 混淆矩阵（Confusion Matrix）：混淆矩阵是一种可视化工具，用于展示模型在每个类别上的分类结果。
它显示了真实类别和预测类别之间的关系，有助于分析模型的误分类情况。
7. ROC曲线（Receiver Operating Characteristic Curve）：ROC曲线是一种绘制真正例率（True Positive Rate）与假正例率（False Positive Rate）之间关系的图表。
它
可以帮助选择合适的分类阈值，并评估模型在不同阈值下的性能。
PRE-TESTPOST-TEST
7: Paired SamplesData and explorationThis chapter considers the analysis of a quantitative outcome based on paired samples. Paired samples (also called dependent samples) are samples in which natural or matched couplings occur. In paired samples, each data point in one sample is matched to a unique data point in the second sample. An example of a paired sample is a pre-test/post-test study design in which a factor is measured before and after an intervention. Paired samples may also be achieved by matching individuals on personal characteristics such as age and sex.In contrast to paired samples, independent samples consider two or unrelated separate groups. Two samples are independent when the data points in one sample are unrelated to the data points in the second sample.It is important to differentiate between paired samples and independent samples. Consider two ways to study the effects of oral contraceptives on blood pressure. Using paired samples, we could take two measurements on individuals in the sample before and again after starting oral contractive. These data are paried because each data point associated with oral contraceptive use would be uniquely matched to the same individual when they were not taking oral contraceptives.We could also study the effects of oral contraceptives on blood pressure in two separate groups of women, one group taking the oral contraceptive and the other taking a placebo. In this instance, data are obtained from unrelated groups and data points in one sample would not be matched to the data points in the second sample.You might ask which type of sample is better, paired or independent? The paired sample offers the benefit of controlling for some of the extraneous factors that influence a woman’s blood pressure. However, sequential samples such as this may still be confounded by independent factors that differ over time. Health outcome may show changes over time due to the influence of these extraneous factors. On the other hand, independent sample have the benefit of having a concurrent control group. Perhaps the best design is a third option in which change within individuals is compared in two independent groups. Illustrative data (oatbran.sav).A study investigated whether oat bran lowers serum cholesterol levels. Fourteen individuals were randomly assigned a diet that included either oat bran or corn flakes. After two weeks on the initial diet, serum low-density lipoprotein levels (mg/dl) were measured. Each subject was then ‘crossed-over” to the alternate diet. After two-weeks on the second diet, low-density lipoprotein levels were was once again recorded. Data are shown on the next page:Illustrative data:ID CORNFLK OATBRAN DELTA1 4.61 3.840.772 6.42 5.570.853 5.40 5.85-0.454 4.54 4.80-0.265 3.98 3.680.306 3.82 2.960.867 5.01 4.410.608 4.34 3.720.629 3.80 3.490.3110 4.56 3.840.7211 5.35 5.260.0912 3.89 3.730.1613 2.25 1.840.4114 4.24 4.140.10We will refer to the CORNFLK data as sample 1 and the OATBRAN data as sample two. Subscripts are attached to summary statistics, so= 4.444 mg/dl and = 4.081 mg/dl.Further analysis requires the creation of a new variable to hold information about the difference within pairs. Let us call this variable DELTA. When creating DELTA values, it makes little difference whether you subtract sample 1 values from sample 2 values or vice versa. It is important, however, to keep track of the direction of the difference. Let DELTA = CORNFLK - OATBRAN. Positive values reflect higher LDL cholesterol on the corn flake diet. All further analyses are directed toward the DELTA variable. Statistics for DELTA are denoted with a subscript of :dn = 14 = 0.363 s = 0.4060d dExploratory graphs are useful in focusing our attention where it ought to be. Here’s a stemplot of the DELTA values:-0|240|0113340|667788(mmol/L)×1Notice that 12 of the 14 observations showed a decrease in LDL levels. The distribution is mound-shaped with no apparent outliers, with a median of 0.3 and range of !0.4 to 0.8.(7.1)dConfidence Interval for :d The parameter : in a matched pair study is the mean difference in responses to the two treatments within matched pairs of individuals in the entire population. The sample mean of DELTAestimates ths value.d We want to get a better sense of how well estimates the true value of : by calculating a confidenced interval for :The approach presented previously is used to calculate the confidence. The point estimate is surrounded d with a margin of error. The sample mean of DELTA is the point estimator of : The margin of error is based on a t critical value and the estimated standard error of the mean difference according to the following formula:n -1,1-"/2where t represents the 1!a/2 percentile on a t distribution with n !1 degrees of freedom and=.Illustrative example (oatbran.sav ), 95% confidence interval. For the illustrative data , n = 14,=d d d 0.363, s = 0.4060, and se == 0.1085. Therefore, 95% confidence interval for :is13, 1-(.05/2)= 0.3629 ± (t )(0.1085)13, .975= 0.3629 ± (t )(0.1085) = 0.3629 ± (2.16)(0.1085) = 0.3629 ± 0.2344 = (0.129, 0.597)We are 95% confident the true mean difference lies between 0.129 and 0.597.Illustrative example (oatbran.sav ), 90% confidence interval. For 90% confidence, use " = .10.The 90% confidence interval13, 1-.(10/2)13, .95= 0.3629 ± (t )(0.1085) = 0.3629 ± (t )(0.1085) = 0.3629 ± (1.77)(0.1085) = 0.3629 ± 0.1920 = (0.171, 0.555)We are 90% confident the true mean difference lies in this interval.(7.2)Hypothesis Test0d Hypotheses: Under the null, we expect no mean. The null hypothesis is H : : = 0. The alterative 1d 1d 1d hypothesis is either H : : < 0 (one-sided to left), H : : > 0 (one-sided to right), or H : : 0 (two-sided).Test statistic: The paired t statistic is:where represents the mean difference in the sample and . This test statistic has df = n !1.stat P-value: The t is converted to a P-value in the usual fashion. Use either the t table or a utility program 0(e.g., StaTable) for this purpose. Low P-value provide evidence against H .Significance (optional): The test is said to be significant at the alpha level of significance when P < ",0in which case H is rejected.dIllustrative example. We’ve established in mean decline in LDL cholesterol on oatbran is = 0.363 (n d = 14, and s = 0.4060).0d 1d •Hypotheses: H : : = 0 versus H : : 0d stat•Test statistic: The standard error of the mean difference se = = 0.1085, the t == 3.34, and df = 14 !1 = 13.stat 13..995 13..999 •P -value: The critical landmarks surrounding the t are t = 3.01 and t = 3.88.Therefore, the one-tailed P-value is less than 0.005 and more than 0.001. The two-sided 0.002 < P < 0.01. The precise P = 0.0053 (by computer). This provides good evidence 0against H .0•Significance (optional): Data are significant at the 0.01; reject H .Power0If H is false and we fail to reject it, we commit a type II error. The probability of a type II error is $, and the probability of avoiding a type II error is 1!$ or “power.”The approximate power of a t test at a = .05 (two-sided) is equal to, where )represents “a difference worth detecting,” s is the population standard deviation (or a reasonably good estimate of this value), and N (phi) is the area under a standard normal curve to the left of the value in parentheses.The difference worth detecting is the difference the investigator is looking for. It is a meaningfuldifference, and is up to the discretion of the investigator. In a study of an anti-hypertensives for instance,a drop of 10 mm Hg might be worth detecting, while a drop of 1 mm Hg might not be worth detecting. In a study on weight loss, a drop of 5 pounds might be meaningful in a population of runway models, but may be meaningless in a morbidly obese population. The amount of the difference worth detecting is a matter of the research.The N (z) function may require further explanation. This is the cumulative probability of z. For instance, f (0) = .5000, since half the area under the Z curve is to the left of 0, i.e., .As an additional example, f (!1.96) = .025, which looks like this:Illustrative example. We want to determine the power of a t test in which a mean difference of 2 is worth detecting. We study 30 observations, and prior studies suggests the variable being studied has a standard deviation of 6. What is the power of the study at " = .05 two-sided? ANS:. We use a Z table to determine that the area under the curve to the rightof !0.13 is 0.4483 (about 45%). This means the test had less than a 50/50 chance of revealing a significant difference of 2 (or more). A test should have at least 80% power. Thus, this test has inadequate power. Increasing the sample size of the study will increase its power.Sample Size Requirements (Optional)When planning a hypothesis test, we need to have an idea of an appropriate size to ensure sufficient power of the test before the study begins. Without such a plan, we might find out that the study had inadequate power to detect a meaningful difference. When conducting statistical tests, an adequate0sample size (n ) is one that will reject H at a given " level with adequate power (1!$) when a difference worth detecting ()) is present in the population.To determine adequate n , we must make the assumption that sampling distributional of the observed mean difference is normal. We must also present some reasonable assumption regarding the variability (F ) of the underlying variable. The value of F is generally unknown and must therefore be estimated from either (a) a preliminary (pilot) study, (b) previously published results from a similar population, (c) intuition, or (d) other past experience.Given these assumptions, the sample size needed to detect a difference of ) at " = .05 (two-sided) for 80% power is equal to(/~gdallal/SIZE.HTM).Illustrative example. To detect ) = 2 for a variable with F = 6, you need n = [(16)(6²) / 2²] + 1 = 145.。
多层陶瓷芯片电容器 NCC-016-1705说明书
1. ScopeThis specification is applied to Multilayer Ceramic Chip Capacitor(MLCC) for use in electric equipment for the voltage is ranging from 4V to 50V.The series suitable for general electrics circuit, telecommunications, personal computers and peripheral, power circuit and mobile application. (This product is compliant with the RoHS & HF.)2. Parts Number Code3. Nominal Capacitance and Tolerance3.1 Standard Combination of Nominal Capacitance and ToleranceClass CharacteristicTolerance Nominal CapacitanceⅡX7RK (± 10.0 %)E-3, E-6 series3.2 E series(standard Number) Standard No.Application CapacitanceE- 3 1.02.24.7E- 6 1.0 1.52.23.34.76.8E-12 1.0 1.2 1.5 1.8 2.2 2.7 3.3 3.9 4.7 5.6 6.8 8.2 E-241.0 1.2 1.5 1.82.2 2.73.3 3.94.75.66.8 8.2 1.1 1.31.62.02.43.0 3.64.35.16.27.5 9.14. Operation Temperature RangeClassCharacteristic Temperature Range Reference Temp.Ⅱ X7R (X)-55 ~ +125℃℃25℃5. Storage ConditionStorage Temperature ：5 to 40℃ Relative Humidity ：20 to 70 % (6)Rated Voltage Code Rated Voltage (Vdc)05050 (1) (2) (3) (4) (5) (6) (7) (1)ProductProduct CodeC Multilayer Ceramic Chip Capacitor(3)Temperature Characteristics Code Temperature Characteristic Temperature Range Temperature Coefficient X X7R -55℃~+125℃ ± 15% (4)Capacitance unit :pico farads(pF)Code Nominal Capacitance (pF) 104 100,000.0 ※. If there is a decimal point, it shall be expressed by an English capital letter R(5)Capacitance Tolerance Code Tolerance Nominal CapacitanceK ± 10.0 % More Than 10 pF (7)TappingCode TypeT Tape & Reel(2)Chip Size Code Length×Width unit : mm(inch) 06031.60× 0.80 (.063× .031)6. Dimensions6.1 Configuration and Dimension ：Unit:mmTYPE LW TB (min)BW (min) 06031.60± 0.100.80± 0.100.85± 0.150.400.156.2 Termination Type ：External Electrodes BarrierInner ElectrodesPolymer Electrodes (If applicable)7. PerformanceWhen operating at temperature range from 100℃to 125℃, the operation shall be carried out at a derating voltage or less as shown belowFig.1P.C. Board for Bending Strength TestMaterial : Glass Epoxy Substrate: Solder ResistTest SubstrateMaterial : Glass Epoxy Substrate: Copper (Thickness : 0.035mm)Thickness : 1.6 mmUnit:mmType A B C 0201 0.2 0.9 0.4 0402 0.5 1.5 0.6 0603 1.0 3.0 1.0 0805 1.2 4.0 1.6 1206 2.2 5.0 2.0 1210 2.2 5.0 2.9 1808 3.5 7.0 2.5 1812 3.5 7.0 3.7 2208 4.5 8.0 2.5 2211 4.5 8.0 3.0 22204.58.05.68. Packing8.1 Bulk PackingAccording to customer request. 8.2 Chip Capacitors Tape Packing8.3 Material And QuantityTape Material 0201 0402 0603/0805 T 0.≦33mm T 0.55mm ≦ T ≦1.00mm T ＞1.00mm Paper 15,000 pcs/Reel 10,000 pcs/Reel 4,000 pcs/Reel NAPlastic NA NA NA 3,000 pcs/ReelTape Material 1206T ≦1.00mm 1.00mm ＜T 1.25mm ≦T ＞1.25mmPaper 4,000 pcs/ReelNANAPlastic NA3,000 pcs/Reel2,000 pcs/ReelTape Material 1808/1210T ≦1.25mm1.25mm ＜T ≦2.40mmT ＞2.40mmPaper NANANAPlastic 3000 pcs/Reel2000 pcs/Reel500/1,000 pcs/ReelTape Material 1812/2211/2220 1825/2225 2208 T ≦2.20mm T ＞2.20mm T ≦2.20mm T ＞2.20mm T ≦2.20mm Paper NA NA NA NA NAPlastic 1000 pcs/Reel 700 pcs/Reel 700 pcs/Reel400 pcs/Reel 1000 pcs/Reel NA ：Not Available8.4 Cover Tape Reel Off Force8.4.1 Peel-Off Force5 g·f Peel ≦-Off Force 70 g ≦·f 8.4.2 Measure Method8.5 Paper TapeUnit:mm8.6 Plastic TapeUnit:mm TYPE A B C DE 0201 0.37± 0.1 0.67± 0.1 4.00± 0.1 2.00± 0.052.00± 0.10402 0.61± 0.1 1.20± 0.1 0603 1.10± 0.2 1.90± 0.2 4.00± 0.10805 1.50± 0.2 2.30± 0.2 1206 1.90± 0.2 3.50± 0.2 1210 2.90± 0.2 3.60± 0.2 TYPE FG H It0201 1.75± 0.103.50± 0.058.0± 0.30 φ1.50 +0.10/-0 1.10 max.0402 0603 0805 1206 1210Type A B C D E F 0805 1.5±0.2 2.3±0.2 4.0± 0.12.0± 0.054.0± 0.11.75± 0.11206 1.9±0.2 3.5±0.2 1210 2.9±0.2 3.6±0.2 1808 2.5±0.2 4.9±0.2 1812 3.6±0.2 4.9±0.2 8.0± 0.11825 6.9±0.2 4.9±0.2 2208 2.5±0.2 6.1±0.2 2211 3.2±0.2 6.1±0.2 2220 5.4±0.2 6.1±0.2 22256.9±0.26.1±0.28.7 Reel DimensionsReel Material ：PolystyreneType G H IJ t O 0805 3.5± 0.058.0± 0.3φ1.5+0.1/-03.0 max.0.3 max.1.0± 0.11206 1210 1808 5.5± 0.05 12.0 ± 0.3 4.0 max. 1.5± 0.11812 1825 2208 2211 2220 2225Type AB C DE W 0201 φ382 max φ50 min φ13± 0.5φ21± 0.82.0±0.510± 0.150402 0603 0805 1206 1210 1808 φ178±0.2 φ60±0.2 13±0.31812 1825 2208 2211 2220 2225Unit:mmPrecautionary Notes:1. StorageStore the capacitors where the temperature and relative humidity don’t exceed 40°C and 70%RH. Werecommend that the capacitors be used within 12 months from the date of manufacturing. Store the products in the original package and do not open the outer wrapped, polyethylene bag, till just before usage. If it is open, seal it as soon as possible or keep it in a desiccant with a desiccation agent.2. Construction of Board PatternImproper circuit layout and pad/land size may cause excessive or not enough solder amount on the PC board. Not enough solder may create weak joint, and excessive solder may increase the potential of mechanical or thermal cracks on the ceramic capacitor. Therefore we recommend the land size to be as shown in the following table: 2.1 Size and recommend land dimensions for reflow soldering2.2 Mechanical strength varies according to location of chip capacitors on the P .C. board.Design layout of components on the PC board such a way to minimize the stress imposed on the components, upon flexure of the boards in depanelization or other processes.Component layout close to the edge of the board or the “depanelization line” is not recommended. Susceptibility to stress is in the order of: a>b>c and d>eEIA Code Chip (mm) Land (mm) L W A B C D E 0201 0.60 0.30 0.2~0.3 0.2~0.4 0.2~0.4 -- -- 0402 1.00 0.50 0.3~0.5 0.3~0.5 0.4~0.6 -- -- 0603 1.60 0.80 0.4~0.6 0.6~0.7 0.6~0.8 -- -- 0805 2.00 1.25 0.7~0.9 0.6~0.8 0.8~1.1 -- -- 1206 3.20 1.60 2.2~2.4 0.8~0.9 1.0~1.4 1.0~2.0 3.2~3.7 1210 3.20 2.50 2.2~2.4 1.0~1.2 1.8~2.3 1.0~2.0 4.1~4.6 1808 4.60 2.00 2.8~3.4 1.8~2.0 1.5~1.8 1.0~2.8 3.6~4.1 1812 4.60 3.20 2.8~3.4 1.8~2.0 2.3~3.0 1.0~2.8 4.8~5.3 1825 4.60 6.35 2.8~3.4 1.8~2.0 5.1~5.8 1.0~4.0 7.1~8.3 2208 5.70 2.00 4.0~4.6 2.0~2.2 1.5~1.8 1.0~4.0 3.6~4.1 2211 5.70 2.80 4.0~4.6 2.0~2.2 2.0~2.6 1.0~4.0 4.4~4.9 2220 5.70 5.00 4.0~4.6 2.0~2.2 3.5~4.8 1.0~4.0 6.6~7.1 2225 5.70 6.354.0~4.62.0~2.2 5.1~5.8 1.0~4.07.1~8.32.3 Layout Recommendation3. Mounting3.1 Sometimes crack is caused by the impact load due to suction nozzle in pick and place operation.In pick and place operation, if the low dead point is too low, excessive stress is applied to component. This maycause cracks in the ceramic capacitor, therefore it is required to move low dead point of a suction nozzle to the higher level to minimize the board warp age and stress on the components. Nozzle pressure is typically adjusted to 1N to 3N (static load) during the pick and place operation.3.2 Amount of Adhesivea0.2mm min. b 70 ~ 100 µm cDo not touch the solder landExample : 0805 & 12064. Soldering4.1. Wave SolderingMost of components are wave soldered with solder at 230 to 250°C. Adequate care must be taken to prevent the potential of thermal cracks on the ceramic capacitors. Refer to the soldering methods below for optimum soldering benefits.Recommend flow soldering temperature ProfileTo optimize the result of soldering, proper preheating is essential: 1) Preheat temperature is too low a. Flux flows to easilyb. Possibility of thermal cracks2) Preheat temperature is too higha. Flux deteriorates even when oxide film is removedb. Causes warping of circuit boardc. Loss of reliability in chip and other componentsCooling Condition:Natural cooling using air is recommended. If the chips are dipped into a solvent for cleaning, the temperature difference (ΔT) between the solvent and the chips must be less than 100°C.4.2 Reflow SolderingPreheat and gradual increase in temperature to the reflow temperature is recommended to decrease the potential of thermal crack on the components. The recommended heating rate depends on the size of component, however it should not exceed 3°C/Sec.Recommend reflow profile for Lead-Free soldering temperature Profile (MIL-STD-202G #210F)Soldering Method Change in Temp.( )℃1206 and Under ΔT 190 ≦℃ 1210 and Over ΔT 130 ≦℃Soldering Method Change in Temp.( )℃ 1206 and UnderΔT ≤ 100~130 max.SolderingT e m p e r a t u r e (°C )T e m p e r a t u r e (°C )※ The cycles of soldering : Twice (max.)4.3 Hand SolderingSudden temperature change in components, results in a temperature gradient recommended in the following table, and therefore may cause internal thermal cracks in the components. In general a hand soldering method is not recommended unless proper preheating and handling practices have been taken. Care must also be taken not to touch the ceramic body of the capacitor with the tip of solder Iron.Soldering Method Change in Temp.( )℃1206 and Under ΔT 1≦50 ℃1210 and Over ΔT 130≦℃How to Solder Repair by Solder Iron1) Selection of the soldering iron tipThe required temperature of solder iron for any type of repair depends on the type of the tip, the substrate material, and the solder land size.2) recommended solder iron conditiona.) Preheating Condition：Board and components should be preheated sufficiently at 150°C or over,and soldering should be conducted with soldering iron as boards and components are maintainedat sufficient temperatures.b.) Soldering iron power shall not exceed 30 W.c.) Soldering iron tip diameter shall not exceed 3mm.d.) Temperature of iron tip shall not exceed 350°C to perform the process within 5 seconds.(refer to MIL-STD-202G)f.) Do not touch the ceramic body with the tip of solder iron. Direct contact of the soldering iron tip to ceramicbody may cause thermal cracks.g.) After soldering operation, let the products cool down gradually in the room temperature.5. Handling after chip mounted5.1 Proper handling is recommended, since excessive bending and twist of the board, depends on the orientationof the chip on the board, may induce mechanical stress and cause internal crack in the capacitor.Temperature(°C)200→Higher potential of crack Lower potential of crack ╳5.3 Mechanical stress due to warping a (a) Crack occurrence ratio will be in (b) Crack occurrence ratio will be in :Tensile Stress ╳6. Handling of Loose Chip Capacitor 6.1 If dropped the chip capacitor may c6.2 In piling and stacking of the P .C. bo may hit the chip capacitor mounted7. Safekeeping condition and period For safekeeping of the products, we re under humidity of 20 to 70% RH. The sing and torsion.be increased by manual separation.be increased by tensile force , rather than compressiv s○ :Compressive Stress tor may crack. .C. boards after mounting for storage or handling, the unted on another board to cause crack.we recommend to keep the storage temperature betwe The shelf life of capacitors is 12 months. ressive force.ess, the corner of the P .C. boardbetween +5 to +40°C and Crack。
人教版高中英语 必修二 Unit4 《Wildlife protection ---Pre-Reading》 课件 (共58张PPT)
If you have seen her/him, please let her/him back. Thanks!
My Mom Lost! My mom is out. Have you seen her? We live in Tibet at a high altitude. She is brown and the stomach is white. The wool beneath her stomach is very,very,very soft. She is so beautiful that she was chosen as one of the mascots for the Beijing Olympic Games named Yingying.
• To employ different reading skills to get, analyze and summarize information. 运用略读和找读策略迅速获取信息,并能够精读文章获 取信息和分析信息。学会总结故事体裁文章主题的方法。
• To express your opinions about Wildlife Protection according to the information you’ve ggeot.. 利用已获取的信息发表自己对野生动物保护问题的看法。
They are beingwkhiylled for the wool beneath their stomachs
Their fur is being used to make sweaters for people.
They’re now an endangered species. result
Unit 4 Wildlife Protection
dictation
UNIT ONE TALENTED (1) NAME___________________ TOTAL___________________PART ONE DICTATION1__________________________________ 2__________________________________ 3__________________________________ 4__________________________________ 5___________________________________ 6___________________________________ 7___________________________________ 8____________________________________ 9____________________________________ 10___________________________________ 11__________________________________ 12__________________________________ 13__________________________________ 14__________________________________ 15___________________________________ 16___________________________________ 17___________________________________ 18___________________________________ 19___________________________________ 20___________________________________PART TWO PARAPHRASING1, If you examined the birth certificates of every soccer player in a World Cup tournament, you would find an unusual tendency: elite soccer players are more likely to have been born earlier in the year than later.2, They’ve come to a rather startling conclusion: practice really does make perfect. What we call ‘talent’ is highly overrated, as expert performers are nearly always made, not born.UNIT ONE TALENTED (2) NAME___________________ TOTAL___________________PART ONE DICTATION1__________________________________ 2__________________________________ 3__________________________________ 4__________________________________ 5___________________________________ 6___________________________________ 7___________________________________ 8____________________________________ 9____________________________________ 10___________________________________ 11__________________________________ 12__________________________________ 13__________________________________ 14__________________________________ 15___________________________________ 16___________________________________ 17___________________________________ 18___________________________________ 19___________________________________ 20___________________________________PART TWO PARAPHRASING1, He may be mistaking maturity for ability but once chosen, those January-born players are the ones who, year after year, receive the training, the deliberate practice, the feedback – and have the accompanying self-esteem – that will turn them into elite players.2, The insight of the researchers can explain the riddle of why so many elite players are born early in the year.UNIT TWO MISUNDERSTANDINGS(1) NAME___________________ TOTAL___________________PART ONE DICTATION1__________________________________ 2__________________________________ 3__________________________________ 4__________________________________ 5___________________________________ 6___________________________________ 7___________________________________ 8____________________________________ 9____________________________________ 10___________________________________ 11__________________________________ 12__________________________________ 13__________________________________ 14__________________________________ 15___________________________________ 16___________________________________ 17___________________________________ 18___________________________________ 19___________________________________ 20___________________________________PART TWO PARAPHRASING1, Suddenly, a wave of water came through the open window and soaked me to the skin!2, It’s all meant to be fun, of course, but by that time I’d lost my sense of humour!3, The research also suggests that when it comes to choosing a life path, you should do what you love.UNIT TWO MISUNDERSTANDINGS(1) NAME___________________ TOTAL___________________PART ONE DICTATION1__________________________________ 2__________________________________ 3__________________________________ 4__________________________________ 5___________________________________ 6___________________________________ 7___________________________________ 8____________________________________ 9____________________________________ 10___________________________________ 11__________________________________ 12__________________________________ 13__________________________________ 14__________________________________ 15___________________________________ 16___________________________________ 17___________________________________ 18___________________________________ 19___________________________________ 20___________________________________PART TWO PARAPHRASING1, I’d heard that the chances of having a parachute malfunction are about one in 750,000 but on my third jump, I hit the side of the plane.2,The strings attached to the canopy got tangled around my legs. I tried to untie them but they were too tight.3, I’ve always had a fear of heights, so one day I volunteered for a jump course.UNIT THREE LEARNERS AND TEACHERS (1) NAME___________________TOTAL___________________PART ONE DICTATION1__________________________________ 2__________________________________ 3__________________________________ 4__________________________________ 5___________________________________ 6___________________________________ 7___________________________________ 8____________________________________ 9____________________________________ 10___________________________________ 11__________________________________ 12__________________________________ 13__________________________________ 14__________________________________ 15___________________________________ 16___________________________________ 17___________________________________ 18___________________________________ 19___________________________________ 20___________________________________PART TWO PARAPHRASING1, The classes offer a great full-body workout for those who want to stay in shape and include more exercise in their weekly routine.2,We offer hands-on learning of this important life skill, so you will be able to act confidently in various emergency situations requiring first aid.UNIT THREE LEARNERS AND TEACHERS (2) NAME___________________TOTAL___________________PART ONE DICTATION1__________________________________ 2__________________________________ 3__________________________________ 4__________________________________ 5___________________________________ 6___________________________________ 7___________________________________ 8____________________________________ 9____________________________________ 10___________________________________ 11__________________________________ 12__________________________________ 13__________________________________ 14__________________________________ 15___________________________________ 16___________________________________ 17___________________________________ 18___________________________________ 19___________________________________ 20___________________________________PART TWO PARAPHRASING1, Seeing his determination and dedication to teaching cleared my doubts.2,The secret of his success, he says is commitment3, From 10am to 4pm, he focuses on his own studies, then he races back to his village to welcome his students at 5pm.UNIT FOUR LOCAL KNOWLEDGE (1) NAME___________________ TOTAL___________________PART ONE DICTATION1__________________________________ 2__________________________________ 3__________________________________ 4__________________________________ 5___________________________________ 6___________________________________ 7___________________________________ 8____________________________________ 9____________________________________ 10___________________________________ 11__________________________________ 12__________________________________ 13__________________________________ 14__________________________________ 15___________________________________ 16___________________________________ 17___________________________________ 18___________________________________ 19___________________________________ 20___________________________________PART TWO PARAPHRASING1, The duration of her songs varied from concert to concert and was based on the interaction between singer and audience.2, But the particular significance of the fifth floor in Hrabal’s life and work has led some to wonder whether his death was an accident or suicide.UNIT FOUR LOCAL KNOWLEDGE (2) NAME___________________ TOTAL___________________PART ONE DICTATION1__________________________________ 2__________________________________ 3__________________________________ 4__________________________________ 5___________________________________ 6___________________________________ 7___________________________________ 8____________________________________ 9____________________________________ 10___________________________________ 11__________________________________ 12__________________________________ 13__________________________________ 14__________________________________ 15___________________________________ 16___________________________________ 17___________________________________ 18___________________________________ 19___________________________________ 20___________________________________PART TWO PARAPHRASING1, Also, for Dylan’s sake, don’t miss the well-stocked Hakuhinkan toy store in Tokyo.2,You go through an enormous red gate, then walk along a row of charming little shops to the temple. It’s a busy area, jammed with people.。
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用所给动词的适当形式填空。 1. I___(go) to school every day. 2. He___(go) out just now. 3. I ___ (have) eggs and toast for breakfast tomorrow morning. 4. When I called him, he___ (have) dinner. 5. The rooms ___(paint) by some workers now. 6. They won't buy new clothes because they___(save) money to buy a new house. 7. You have failed to do what___(expect) to and I am afraid the teacher will blame you.
பைடு நூலகம்
• 15.The trees should___(water) often after they___(plant). • 16. Everyone____(think) I come from Sichuan. Actually, I come from Shandong. • 17. In the past five years, there___(be)great changes in my hometown. • 18. Don't make so much noise. The children ___(have) an English lesson. • 19. Mrs White___(cook) dinner when her son came home. • 20. It will be two days before the decision ___(make).
• 8. More than ten robbers ___(arrest) by the police last night. • 9. The play___(show) again next month. • 10. She__(teach) us since I came to this school. • 11. Jim said he ___(take) part in the sports meeting. • 12. By the end of last year, Henry___(collect) more tahn 1, 000 stamps. • 13. I can't see any coffee in the cupboard. It___(finish). • 14. Just now he__(be) asked if the meeting ___(hold) next Friday.