</FONT></B><p><P align=center 0cm 0pt; TEXT-ALIGN: center?><B><FONT face="Times New Roman"><p></FONT></B><p><P 0cm 0pt; TEXT-INDENT: 10.5pt? mso-char-indent-count: mso-char-indent-size: 10.5pt; 1.0;><FONT face="Times New Roman">geology </FONT>地质学<FONT face="Times New Roman"> decimal </FONT>小数,十进小数</P><P 0cm 0pt; TEXT-INDENT: 10.5pt? mso-char-indent-count: mso-char-indent-size: 10.5pt; 1.0;><FONT face="Times New Roman">biology </FONT>生物学<FONT face="Times New Roman"> discipline </FONT>学科</P><P 0cm 0pt; TEXT-INDENT: 10.5pt? mso-char-indent-count: mso-char-indent-size: 10.5pt; 1.0;><FONT face="Times New Roman">social sciences </FONT>社会科学<FONT face="Times New Roman"> contemporary </FONT>现代的</P><P 0cm 0pt; TEXT-INDENT: 10.5pt? mso-char-indent-count: mso-char-indent-size: 10.5pt; 1.0;><FONT face="Times New Roman">disk (disc) </FONT>圆盘<FONT face="Times New Roman"> bacteria </FONT>细菌</P><P 0cm 0pt; TEXT-INDENT: 10.5pt? mso-char-indent-count: mso-char-indent-size: 10.5pt; 1.0;><FONT face="Times New Roman">isosceles triangle </FONT>等腰三角形<FONT face="Times New Roman"> elastic </FONT>弹性的</P><P 0cm 0pt; TEXT-INDENT: 10.5pt? mso-char-indent-count: mso-char-indent-size: 10.5pt; 1.0;><FONT face="Times New Roman">perimeter </FONT>周长<FONT face="Times New Roman"> impetus </FONT>动力</P><P 0cm 0pt; TEXT-INDENT: 10.5pt? mso-char-indent-count: mso-char-indent-size: 10.5pt; 1.0;><FONT face="Times New Roman">volume </FONT>体积<FONT face="Times New Roman"> proportional to </FONT>与…成比例</P><P 0cm 0pt; TEXT-INDENT: 10.5pt? mso-char-indent-count: mso-char-indent-size: 10.5pt; 1.0;><FONT face="Times New Roman">center </FONT>中心<FONT face="Times New Roman"> inscribe </FONT>内接</P><P 0cm 0pt; TEXT-INDENT: 10.5pt? mso-char-indent-count: mso-char-indent-size: 10.5pt; 1.0;><FONT face="Times New Roman">steepness </FONT>斜度<FONT face="Times New Roman"> solid sphere </FONT>实心球</P><P 0cm 0pt; TEXT-INDENT: 10.5pt? mso-char-indent-count: mso-char-indent-size: 10.5pt; 1.0;><FONT face="Times New Roman">method of exhaustion </FONT>穷举法<FONT face="Times New Roman"> refinement </FONT>精炼,提炼</P><P 0cm 0pt; TEXT-INDENT: 10.5pt? mso-char-indent-count: mso-char-indent-size: 10.5pt; 1.0;><FONT face="Times New Roman">polygon </FONT>多边形,多角形<FONT face="Times New Roman"> cumbersome </FONT>笨重的,麻烦的</P><P 0cm 0pt; TEXT-INDENT: 10.5pt? mso-char-indent-count: mso-char-indent-size: 10.5pt; 1.0;><FONT face="Times New Roman">polygonal </FONT>多角形<FONT face="Times New Roman"> fragmentary </FONT>碎片的,不完全的</P><P 0cm 0pt; TEXT-INDENT: 10.5pt? mso-char-indent-count: mso-char-indent-size: 10.5pt; 1.0;><FONT face="Times New Roman">approximation </FONT>近似,逼近<FONT face="Times New Roman"> background </FONT>背景</P><P 0cm 0pt?><FONT face="Times New Roman"><p></FONT><p><P 0cm 0pt?><FONT face="Times New Roman"><p></FONT><p><P 0cm 0pt?><FONT face="Times New Roman"><p></FONT><p>
数学专业英语[12]-The Normal Distribution
<P><FONT face="Times New Roman" size=3>We shall begin by considering some simple continuously variable quantity like stature.We know this varies greatly from one individual to another ,and may also expect to find certain average differences between people drawn from different social classes or living in different geographical areas,etc.Let us suppose that a socio-medical survey of a particular community has provided us with a representative sample of 117 males whose heights are distributed as shown in the first and third columns of Table 1.</FONT></P><P><FONT face="Times New Roman"><FONT size=3>
</FONT></FONT>
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<P><FONT face="Times New Roman"><FONT size=3>
<p></FONT></FONT>
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<P><FONT face="Times New Roman" size=3>Table 1.Distribution of stature in 117 males </FONT></P>
<TABLE cellSpacing=0 cellPadding=0 border=1>
<TR>
<TD vAlign=top width=91>
<P><FONT face="Times New Roman">Absolute </FONT></P>
<P><FONT face="Times New Roman">Height</FONT></P>
<P><FONT face="Times New Roman">(m)</FONT></P></TD>
<TD vAlign=top width=108>
<P><FONT face="Times New Roman">Working </FONT></P>
<P><FONT face="Times New Roman">measurements </FONT></P>
<P><FONT face="Times New Roman">with origin</FONT></P>
<P><FONT face="Times New Roman">at 1.70(x)</FONT></P></TD>
<TD vAlign=top width=96>
<P><FONT face="Times New Roman">Number of </FONT></P>
<P><FONT face="Times New Roman">men</FONT></P>
<P><FONT face="Times New Roman">observed(f) </FONT></P></TD>
<TD vAlign=top width=96>
<P><FONT face="Times New Roman">Contributions</FONT></P>
<P><FONT face="Times New Roman">to the sum </FONT></P>
<P><FONT face="Times New Roman">(f x )</FONT></P></TD>
<TD vAlign=top width=120>
<P><FONT face="Times New Roman">Contributions</FONT></P>
<P><FONT face="Times New Roman">to the sum of </FONT></P>
<P><FONT face="Times New Roman">squares (f </FONT><v:shapetype><v:stroke joinstyle="miter"></v:stroke><v:formulas><v:f eqn="if lineDrawn pixelLineWidth 0"></v:f><v:f eqn="sum @0 1 0"></v:f><v:f eqn="sum 0 0 @1"></v:f><v:f eqn="prod @2 1 2"></v:f><v:f eqn="prod @3 21600 pixelWidth"></v:f><v:f eqn="prod @3 21600 pixelHeight"></v:f><v:f eqn="sum @0 0 1"></v:f><v:f eqn="prod @6 1 2"></v:f><v:f eqn="prod @7 21600 pixelWidth"></v:f><v:f eqn="sum @8 21600 0"></v:f><v:f eqn="prod @7 21600 pixelHeight"></v:f><v:f eqn="sum @10 21600 0"></v:f></v:formulas><v:path extrusionok="f" connecttype="rect" gradientshapeok="t"></v:path><LOCK aspectratio="t" v:ext="edit"></LOCK></v:shapetype><v:shape><v:imagedata><FONT face="Times New Roman"></FONT></v:imagedata></v:shape><FONT face="Times New Roman">)</FONT></P></TD></TR>
<TR>
<TD vAlign=top width=91>
<P><FONT face="Times New Roman">1.58</FONT></P>
<P><FONT face="Times New Roman">1.60</FONT></P>
<P><FONT face="Times New Roman">1.62</FONT></P>
<P><FONT face="Times New Roman">1.64</FONT></P>
<P><FONT face="Times New Roman">1.66</FONT></P>
<P><FONT face="Times New Roman">1.68</FONT></P>
<P><FONT face="Times New Roman">1.70</FONT></P>
<P><FONT face="Times New Roman">1.72</FONT></P>
<P><FONT face="Times New Roman">1.74</FONT></P>
<P><FONT face="Times New Roman">1.76</FONT></P>
<P><FONT face="Times New Roman">1.78</FONT></P>
<P><FONT face="Times New Roman">1.80</FONT></P>
<P><FONT face="Times New Roman">1.82</FONT></P>
<P><FONT face="Times New Roman">1.84</FONT></P></TD>
<TD vAlign=top width=108>
<P>-<FONT face="Times New Roman">6</FONT></P>
<P>-<FONT face="Times New Roman">5</FONT></P>
<P>-<FONT face="Times New Roman">4</FONT></P>
<P>-<FONT face="Times New Roman">3</FONT></P>
<P>-<FONT face="Times New Roman">2</FONT></P>
<P>-<FONT face="Times New Roman">1</FONT></P>
<P><FONT face="Times New Roman">0</FONT></P>
<P><FONT face="Times New Roman">1</FONT></P>
<P><FONT face="Times New Roman">2</FONT></P>
<P><FONT face="Times New Roman">3</FONT></P>
<P><FONT face="Times New Roman">4</FONT></P>
<P><FONT face="Times New Roman">5</FONT></P>
<P><FONT face="Times New Roman">6</FONT></P>
<P><FONT face="Times New Roman">7</FONT></P></TD>
<TD vAlign=top width=96>
<P><FONT face="Times New Roman">1</FONT></P>
<P><FONT face="Times New Roman">3</FONT></P>
<P><FONT face="Times New Roman">6</FONT></P>
<P><FONT face="Times New Roman">8</FONT></P>
<P><FONT face="Times New Roman">13</FONT></P>
<P><FONT face="Times New Roman">18</FONT></P>
<P><FONT face="Times New Roman">19</FONT></P>
<P><FONT face="Times New Roman">14</FONT></P>
<P><FONT face="Times New Roman">14</FONT></P>
<P><FONT face="Times New Roman">9</FONT></P>
<P><FONT face="Times New Roman">5</FONT></P>
<P><FONT face="Times New Roman">4</FONT></P>
<P><FONT face="Times New Roman">2</FONT></P>
<P><FONT face="Times New Roman">1</FONT></P></TD>
<TD vAlign=top width=96>
<P>-<FONT face="Times New Roman">6</FONT></P>
<P>-<FONT face="Times New Roman">15</FONT></P>
<P>-<FONT face="Times New Roman">24</FONT></P>
<P>-<FONT face="Times New Roman">24</FONT></P>
<P>-<FONT face="Times New Roman">26</FONT></P>
<P>-<FONT face="Times New Roman">18</FONT></P>
<P><FONT face="Times New Roman">0</FONT></P>
<P><FONT face="Times New Roman">14</FONT></P>
<P><FONT face="Times New Roman">28</FONT></P>
<P><FONT face="Times New Roman">27</FONT></P>
<P><FONT face="Times New Roman">20</FONT></P>
<P><FONT face="Times New Roman">20</FONT></P>
<P><FONT face="Times New Roman">12</FONT></P>
<P><FONT face="Times New Roman">7</FONT></P></TD>
<TD vAlign=top width=120>
<P><FONT face="Times New Roman">36</FONT></P>
<P><FONT face="Times New Roman">75</FONT></P>
<P><FONT face="Times New Roman">96</FONT></P>
<P><FONT face="Times New Roman">72</FONT></P>
<P><FONT face="Times New Roman">52</FONT></P>
<P><FONT face="Times New Roman">18</FONT></P>
<P><FONT face="Times New Roman">0</FONT></P>
<P><FONT face="Times New Roman">14</FONT></P>
<P><FONT face="Times New Roman">56</FONT></P>
<P><FONT face="Times New Roman">81</FONT></P>
<P><FONT face="Times New Roman">80</FONT></P>
<P><FONT face="Times New Roman">100</FONT></P>
<P><FONT face="Times New Roman">72</FONT></P>
<P><FONT face="Times New Roman">49</FONT></P></TD></TR>
<TR>
<TD vAlign=top width=91>
<P>T<FONT face="Times New Roman">otals</FONT></P></TD>
<TD vAlign=top width=108>
<P><FONT face="Times New Roman">
<p></FONT>
<p></TD>
<TD vAlign=top width=96>
<P><FONT face="Times New Roman">117</FONT></P></TD>
<TD vAlign=top width=96>
<P>+<FONT face="Times New Roman">15</FONT></P></TD>
<TD vAlign=top width=120>
<P><FONT face="Times New Roman">801</FONT></P></TD></TR></TABLE>
<P><FONT size=3><FONT face="Times New Roman">
<p></FONT></FONT>
<p>
<P><FONT size=3><FONT face="Times New Roman"> We shall assume that the original measurements were made as accurately as possible,but that they are given here only to the mearest 0.02 m (i.e.2 cm).Thus the group labeled “1.66” contains all those men whose true measurements were between 1065 and 1067 m.One si biable to run into trouble if the exact methods of recording the measurements and grouping them are not specified exactly.In the example just given the mid-point of the interval labeled”1.66” m.But suppose that the original readings were made only to the nearest 0.01 m (i.e. 1 cm )and then “rounded up “to the nearest multiple of 0.02 m.We should then have “1.65”, which covers the range 1.645 to 1.655,included with “1.66”.The interval “1.66”would then contain all measurements lying between 1.645 m and 1.665 m .for which the mid-point is 1.655 m. The difference of 5 mm from the supposed value of 1.66 m could lead to serious inaccuracy in certain types of investigation.</FONT></FONT></P>
<P><v:group><LOCK aspectratio="t" v:ext="edit" position="t" rotation="t"></LOCK><v:shape><FONT size=3><FONT face="Times New Roman"><v:fill detectmouseclick="t"></v:fill><v:path extrusionok="t" connecttype="none"></v:path><LOCK v:ext="edit" text="t"></LOCK></FONT></FONT></v:shape><v:line><FONT face="Times New Roman" size=3></FONT></v:line><v:line><FONT face="Times New Roman" size=3></FONT></v:line><v:line><FONT face="Times New Roman" size=3></FONT></v:line><v:line><FONT face="Times New Roman" size=3></FONT></v:line><v:line><FONT face="Times New Roman" size=3></FONT></v:line><v:line><FONT face="Times New Roman" size=3></FONT></v:line><v:line><FONT face="Times New Roman" size=3></FONT></v:line><v:line><FONT face="Times New Roman" size=3></FONT></v:line><v:line><FONT face="Times New Roman" size=3></FONT></v:line><v:line><FONT face="Times New Roman" size=3></FONT></v:line><v:line><FONT face="Times New Roman" size=3></FONT></v:line><v:line><FONT face="Times New Roman" size=3></FONT></v:line><v:line><FONT face="Times New Roman" size=3></FONT></v:line><v:line><FONT face="Times New Roman" size=3></FONT></v:line><v:line><FONT face="Times New Roman" size=3></FONT></v:line><v:line><FONT face="Times New Roman" size=3></FONT></v:line><v:line><FONT face="Times New Roman" size=3></FONT></v:line><v:line><FONT face="Times New Roman" size=3></FONT></v:line><v:line><FONT face="Times New Roman" size=3></FONT></v:line><v:line><FONT face="Times New Roman" size=3></FONT></v:line><v:line><FONT face="Times New Roman" size=3></FONT></v:line><v:line><FONT face="Times New Roman" size=3></FONT></v:line><v:line><FONT face="Times New Roman" size=3></FONT></v:line><v:line><FONT face="Times New Roman" size=3></FONT></v:line><v:line><FONT face="Times New Roman" size=3></FONT></v:line><v:line><FONT face="Times New Roman" size=3></FONT></v:line><v:line><FONT face="Times New Roman" size=3></FONT></v:line><v:line><FONT face="Times New Roman" size=3></FONT></v:line><v:line><FONT face="Times New Roman" size=3></FONT></v:line><v:line><FONT face="Times New Roman" size=3></FONT></v:line><v:line><FONT face="Times New Roman" size=3></FONT></v:line><v:shape><v:path arrowok="t"><FONT face="Times New Roman" size=3></FONT></v:path></v:shape><v:line><FONT face="Times New Roman" size=3></FONT></v:line><v:line><FONT face="Times New Roman" size=3></FONT></v:line><v:line><FONT face="Times New Roman" size=3></FONT></v:line><v:line><FONT face="Times New Roman" size=3></FONT></v:line><v:line><FONT face="Times New Roman" size=3></FONT></v:line><v:line><FONT face="Times New Roman" size=3></FONT></v:line><v:line><FONT face="Times New Roman" size=3></FONT></v:line><v:line><FONT face="Times New Roman" size=3></FONT></v:line><v:line><v:stroke endarrow="block"><FONT face="Times New Roman" size=3></FONT></v:stroke></v:line><w:anchorlock></w:anchorlock></v:group><v:shape><FONT size=3><FONT face="Times New Roman"><v:imagedata cropbottom="65520f" croptop="-65520f"></v:imagedata><LOCK v:ext="edit" position="t" rotation="t"></LOCK></FONT></FONT></v:shape></P> A convenient visual way of presenting such data is shown in fig. 1, in which the area of each rectangle is ,on the scale used, equal to the observed proportion or percentage of individuals whose height falls in the corresponding group.The total area covered by all the rectangles therefore adds up to unity or 100per cent .This diagram is called a histogram.It is easily constructed when ,sa here ,all the groups are of the same width.It is also easily adapted to the case when the intervals are uneqal, provided we remember that the areas of the rectangles must be proportional to the numbers of units concerned.If, for example, we wished to group togcther the entries for the three groups 1.80,1.82 and 1.84 m,totaling 7 individuals or 6 per cent of the total,then we should need a rectangle whose base covered 3working groups on the horizontal scale but whose height was only 2 units on the vertical scale shown in the diagram.In this way we can make allowance for unequal grouping intervals ,but it is usually less troublesome if we can manageto keep them all the same width.In some books histograms are drawn so that the area of each rectangle is equal to the actual number (instend of the proportion) of individuals in the corresponding group.It is better, however, to use proportions, sa different histograms can then be compared directly. <P 0cm 0pt?><FONT face="Times New Roman">The general appearance of the rectangles in Fig.1 is quite striking ,especially the tall hump in the centre and the rapidly falling tails on each side.There are certain minor irregularities in the pattern, and these would, in general ,be more ronounced if the size of the sample were smaller. Conversely, weth larger samples we usually find that the set of rectangles presents a more regular appearance. This suggests that if we had a very large number of measurements ,the ultimate shape of the picture for a suitably small width of rectangle would be something very like a smooth curve,Such a curve could be regarded as representing the true ,theoretical or ideal distribution of heights in a very (or ,better,infinitely)large population of individuals.</FONT></P><P 0cm 0pt?><FONT face="Times New Roman"> What sort of ideal curve can we expect ? There are seveala theoretical reasons for expecting the so-called Gaussiao or “normal “curve to turn up in practice;and it is an empirical fact that such a curve lften describes with sufficient accuracy the shape of histograms based on large numbers of obscrvations. Moreover,the normal curve is one of the easiest to handle theoretically,and it leads to types of statistical analysis that can be carried out with a minimum amount of computation. Hence the central importance of this distribution in statistical work .</FONT></P><P 0cm 0pt?><FONT face="Times New Roman"> The actual mathematical equation of the normal curve is where u is the mean or average value and </FONT><v:shapetype><v:stroke joinstyle="miter"></v:stroke><v:formulas><v:f eqn="if lineDrawn pixelLineWidth 0"></v:f><v:f eqn="sum @0 1 0"></v:f><v:f eqn="sum 0 0 @1"></v:f><v:f eqn="prod @2 1 2"></v:f><v:f eqn="prod @3 21600 pixelWidth"></v:f><v:f eqn="prod @3 21600 pixelHeight"></v:f><v:f eqn="sum @0 0 1"></v:f><v:f eqn="prod @6 1 2"></v:f><v:f eqn="prod @7 21600 pixelWidth"></v:f><v:f eqn="sum @8 21600 0"></v:f><v:f eqn="prod @7 21600 pixelHeight"></v:f><v:f eqn="sum @10 21600 0"></v:f></v:formulas><v:path extrusionok="f" connecttype="rect" gradientshapeok="t"></v:path><LOCK aspectratio="t" v:ext="edit"></LOCK></v:shapetype><v:shape><v:imagedata><FONT face="Times New Roman"></FONT></v:imagedata></v:shape><v:shape><v:imagedata><FONT face="Times New Roman"></FONT></v:imagedata></v:shape><FONT face="Times New Roman">is the standard deviation, which is a measure of the concentration of frequency about the mean. More will be said about </FONT><v:shape><v:imagedata><FONT face="Times New Roman"></FONT></v:imagedata></v:shape><FONT face="Times New Roman">and </FONT><v:shape><v:imagedata><FONT face="Times New Roman"></FONT></v:imagedata></v:shape><FONT face="Times New Roman">later .The ideal variable x may take any value from </FONT><v:shape><v:imagedata><FONT face="Times New Roman"></FONT></v:imagedata></v:shape><FONT face="Times New Roman">to </FONT><v:shape><v:imagedata><FONT face="Times New Roman"></FONT></v:imagedata></v:shape><FONT face="Times New Roman">.However ,some real measurements,like stature, may be essentially positive. But if small values are very rare ,the ideal normal curve may be a sufficiently close approximation. Those readers who are anxious to avoid as much algebraic manipulation as possible can be reassured by the promise that no derect use will be made in this book of the equation shown. Most of the practical numerical calculations to which it leads are fairly simple.</FONT></P><P 0cm 0pt?><FONT face="Times New Roman"> Fig. 1 shows a normal curve, with its typocal symmetrical bell shape , fitted by suitable methods to the data embodied in the rectangles. This is not to say that the fitted curve is actually the true, ideal one to which the histogram approxime.tes; it is merely the best approximation we can find.</FONT></P><P 0cm 0pt?><FONT face="Times New Roman"> The mormal curve used above is the curve we have chosen to represent the frequency distribution of stature for thr ideal or infinitely large population. This ideal poplation should be contrasted with the limited sample of obsrever. Values that turns up on any occasion when we make actual measurements in the real world. In the survey mentioned above we had a sample of 117 men .If the community were sufficiently large for us to collect several samples of this size, we should find that few if any of the corresponding histograms were exactly the same ,although they might all be taken as illustrating the underlying frequency distribution. The differences between such histograms constitute what we call sampling variation, and this becomes more prominent at the size of sample decreases</FONT></P> <P align=center 0cm 0pt; TEXT-ALIGN: center?><B><FONT face="Times New Roman">Vocabulary
</FONT></B><p><P 0cm 0pt?><FONT face="Times New Roman">Socio-medical survey </FONT>社会医疗调查表<FONT face="Times New Roman"> visual </FONT>可见的。</P><P 0cm 0pt?><FONT face="Times New Roman">distribute </FONT>分布(动词)<FONT face="Times New Roman"> percentage </FONT>百分比</P><P 0cm 0pt?><FONT face="Times New Roman">distribution </FONT>分布(名词)<FONT face="Times New Roman"> individual </FONT>个人,个别</P><P 0cm 0pt?><FONT face="Times New Roman">histogram </FONT>直方图,矩形图<FONT face="Times New Roman"> mean </FONT>平均值,中数</P><P 0cm 0pt?><FONT face="Times New Roman">hump </FONT>驼背,使隆起<FONT face="Times New Roman"> standard deviation </FONT>标准差</P><P 0cm 0pt?><FONT face="Times New Roman">normal distribution </FONT>正态分布<FONT face="Times New Roman"> sample varianice </FONT>样本方差</P>
数学专业英语[13]-Operations Research
<TABLE width="90%" border=0><TR>
<TD width="100%"><IMG src="http://www.shumo.com/bbs/Skins/Default/topicface/face1.gif" align=absMiddle border=0> <B>数学专业英语-Operations Research</B>
<P><FONT size=3><FONT face="Times New Roman">The start of operations research took place in a military context in the United Kingdom during World War </FONT>Ⅱ<FONT face="Times New Roman">, and it was quickly taken up under the name operations research (OR) in the United States. After the war it evolved in connection with industrial organization, and its many techniques allowed for expanding areas of application in the United States, the United Kingdom, and in other industrial countries. It is, however, not easy to give a precise definition of operations research, There are three different representative definitions.</FONT></FONT></P>
<P><FONT face="Times New Roman" size=3>According to the classical definition, due to P. M. Morse and G. E. Kimball, operations research is a scientific method of providing executives with a quantitative basis for decisions regarding operations under their control.</FONT></P>
<P><FONT face="Times New Roman" size=3>The second definition, due to C. W. Churchman, R. L. Ackoff, and E. L. Arnoff, is as follows: operations research in the most general sense can be characterized as the application of scientific methods, techniques, and tools to the operations of systems so as to provide those in control with optimum solutions to problems.</FONT></P>
<P><FONT face="Times New Roman" size=3>As the third definition we mention the suggestion due to S. Beer: operations research is the attack of modern science on problems of likelihood (accepting mischance) that arise in the management and control of men, machines, materials, and money in their natural environments. Its special technique is to invent a strategy of control by measuring, comparing, and predicting probable behaviour through a scientific model of a situation.</FONT></P>
<P><FONT face="Times New Roman" size=3>These three definitions have several common features. In the first place, operations research serves executives by providing partial observations and advice which they can use in judging a situation. Second, the applicability of operations research is limited to areas where scientific methods can be successfully applied. This is the reason why operations research would not be considered to extend beyond only partial observation and advice. A fundamental requirement for a scientific approach is that it must have a mathematical model whose validity can be tested by actual data, Third, any operation should satisfy three necessary conditions in order that it may be an object of scientific approach: (1) the operation should be defined objectively; (2) the results, consequences, and effects of its application should be objectively measurable; (3) the operation should be capable of repetition. Fourth , operations research should aim at finding a practical strategy. Although operations research is based on scientific methodology, it does not aim at establishing general scientific assertions that are valid for all situstions.</FONT></P>
<P><FONT face="Times New Roman" size=3>These four points are essential to any operations research, and are implicit in each of the three aforementioned definitions.</FONT></P>
<P><FONT face="Times New Roman" size=3>On the other hand these three definitions emphasize differently some specific features of operations research, according to their historical positions. In comparion with the first definition, the second makes clearer the place where operations research is applied by pointing out that it is concerned with the operations of systems, and, instead of the vague mention of quantitative basis for decisions in the first definition, it states that operations research seeks optimum solutions, reflecting a stage where optimum solutions were sought by applications of mathematical programming techniques. In the third definition of operations research the notion of system is defined explicitly, the notion of operation is defined to be its special technique, and the objectives of operations research are given. It is clearly asserted that operations research belongs to the methodology of applied sciences. In operations research, operations and systems are dealt with in their intimate interconnection. The methodology of operations research therefore relies on an overall approach for which interdisciplinary cooperation is indispensable and in which the operations research team plays an important role. </FONT></P>
<P><FONT face="Times New Roman" size=3>In applying the operations research approach to the circumstances with which we are concerned, we concentrate our interest on mutual relationships among input and output characteristics. A black-box method by which the interrelation between input and output can be clarified without entering the actual mechanism of the transformation yielded by the system or by its subsystems plays a fundamental role in operations research. The following are major phases of an operations research project: (1) formulating the problem; (2) constructing a mathematical model to represent the system under study and deriving a solution from the model; (3) testing the model and the solution derived form it; (4) the implementation stage of establishing controls over the solution and putting it to work. It is important to construct a model of information communication in connection. With a mathematical model of any problem in operations research. Process of aliocation, competition, queuing, inventory, and production appear frequently in the mathematical models of operations research.</FONT></P>
<P><FONT face="Times New Roman"><FONT size=3>
</FONT></FONT>
<p>
<P><FONT size=3><FONT face="Times New Roman"> </FONT>——<FONT face="Times New Roman">From Encyclopedic Dictionary </FONT></FONT></P>
<P><FONT size=3><FONT face="Times New Roman"> of Mathematics</FONT></FONT></P>
<P><FONT size=3><FONT face="Times New Roman">
<p></FONT></FONT>
<p>
<P><FONT size=3><FONT face="Times New Roman">
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</TD></TR></TABLE> <P align=center 0cm 0pt; TEXT-ALIGN: center?><B><FONT face="Times New Roman">Vocabulary
</FONT></B><p><P 0cm 0pt; TEXT-INDENT: 27pt?><FONT face="Times New Roman"><p></FONT><p><P 0cm 0pt; TEXT-INDENT: 27pt?><FONT face="Times New Roman">Operations research (OR) </FONT>运筹<FONT face="Times New Roman"> interdiscipline </FONT>交叉学科</P><P 0cm 0pt; TEXT-INDENT: 27pt?><FONT face="Times New Roman">Executive </FONT>行政人员<FONT face="Times New Roman"> interdisciplinary cooperation </FONT>交叉学科的</P><P 0cm 0pt; TEXT-INDENT: 27pt?><FONT face="Times New Roman">likelihood </FONT>似然<FONT face="Times New Roman"> </FONT>合作<FONT face="Times New Roman"> </FONT></P><P 0cm 0pt; TEXT-INDENT: 27pt?><FONT face="Times New Roman">scientific approach </FONT>科学方法<FONT face="Times New Roman"> black-box method </FONT>黑箱方法</P><P 0cm 0pt; TEXT-INDENT: 27pt?><FONT face="Times New Roman">methodology </FONT>方法论<FONT face="Times New Roman"> implementation stage </FONT>实现阶段</P><P 0cm 0pt; TEXT-INDENT: 27pt?><FONT face="Times New Roman">aforementioned </FONT>前述的<FONT face="Times New Roman"> queue </FONT>排队</P><P 0cm 0pt; TEXT-INDENT: 27pt?><FONT face="Times New Roman">mathematical programming </FONT>数学规划</P> <P 0cm 0pt; TEXT-INDENT: 27pt?><B><FONT face="Times New Roman">Notes</FONT></B></P><P 0cm 0pt; TEXT-INDENT: 27pt?><FONT face="Times New Roman">
</FONT><p><P 0cm 0pt tab-stops: TEXT-INDENT: mso-list: level1 list -18pt; 45pt; 45.0pt; l67 lfo50?><FONT face="Times New Roman">1. Operations Research</FONT>运筹学<FONT face="Times New Roman">. </FONT>运筹学是第二次世界大战期间<FONT face="Times New Roman">,</FONT>为解决后勤供应问题而发展起来的一门学科<FONT face="Times New Roman">,</FONT>它运用最优化技术去解决管理和决策问题<FONT face="Times New Roman">.</FONT></P><P 0cm 0pt tab-stops: TEXT-INDENT: mso-list: level1 list -18pt; 45pt; 45.0pt; l67 lfo50?><FONT face="Times New Roman">2. According to the classical definition, due to P. M. Morse and G. E. Kimball, operations research is a scientific method of providing executives with a quantitive basis for decisions regarding operations under their control.</FONT></P><P 0cm 0pt 45pt?>意思是<FONT face="Times New Roman">:</FONT>根据<FONT face="Times New Roman">P. M. Morse</FONT>和<FONT face="Times New Roman">G. E. Kimball</FONT>提出的古典定义<FONT face="Times New Roman">,</FONT>运筹学是一种科学方法<FONT face="Times New Roman">,</FONT>它提供行政人员一种定量基础<FONT face="Times New Roman">,</FONT>以便他们对所控的操作进行决策<FONT face="Times New Roman">,</FONT>这里<FONT face="Times New Roman">due to</FONT>是<FONT face="Times New Roman">”</FONT>归功于<FONT face="Times New Roman">” “</FONT>由…提出<FONT face="Times New Roman">”</FONT>之意<FONT face="Times New Roman">,providing</FONT>…<FONT face="Times New Roman">with</FONT>…<FONT face="Times New Roman">for</FONT>…是<FONT face="Times New Roman">”</FONT>提供…给…用于…<FONT face="Times New Roman">”</FONT>之意<FONT face="Times New Roman">.</FONT></P><P 0cm 0pt tab-stops: TEXT-INDENT: mso-list: level1 list -18pt; 45pt; 45.0pt; l67 lfo50?><FONT face="Times New Roman">3. </FONT>…<FONT face="Times New Roman">instead of the vague mention of quantitative basis for decisions in the first definition, it states that </FONT>…<FONT face="Times New Roman">by applications of mathematical programming techniques.</FONT></P><P 0cm 0pt 45pt?>意思是<FONT face="Times New Roman">:</FONT>代替第意个定义中对于决策的定量基础那种模糊的提法<FONT face="Times New Roman">,</FONT>它<FONT face="Times New Roman">(</FONT>第二个定义<FONT face="Times New Roman">)</FONT>阐明了运筹学用于寻求最优解<FONT face="Times New Roman">,</FONT>反映了运用数学规划方法求最优解的阶段<FONT face="Times New Roman">.</FONT>这里<FONT face="Times New Roman">reflecting</FONT>至句子结束一段<FONT face="Times New Roman">,</FONT>属独立分词结构<FONT face="Times New Roman">,</FONT>用以补充说明<FONT face="Times New Roman">it states that</FONT>…的句子<FONT face="Times New Roman">.</FONT></P><P 0cm 0pt tab-stops: TEXT-INDENT: mso-list: level1 list -18pt; 45pt; 45.0pt; l67 lfo50?><FONT face="Times New Roman">4. The methodology of operations research therefore relies on</FONT>…<FONT face="Times New Roman">the operations research team plays an important role.</FONT></P><P 0cm 0pt 45pt?>意思是<FONT face="Times New Roman">:</FONT>因而运筹学的方法论依赖于…一种全面的研究<FONT face="Times New Roman">,</FONT>对这种研究来说<FONT face="Times New Roman">,</FONT>各交叉学科的合作是不可避免的<FONT face="Times New Roman">,</FONT>而且<FONT face="Times New Roman">,</FONT>在这种研究中<FONT face="Times New Roman">,</FONT>运筹学小组起了重要的作用<FONT face="Times New Roman">.</FONT>注意<FONT face="Times New Roman">:</FONT>前后两个<FONT face="Times New Roman">which</FONT>都是<FONT face="Times New Roman">approach</FONT>的关系代词<FONT face="Times New Roman">,</FONT>很容易误认为第二个<FONT face="Times New Roman">which </FONT>是<FONT face="Times New Roman">cooperation</FONT>的关系代词<FONT face="Times New Roman">,</FONT>虽然这在意思上说得过去<FONT face="Times New Roman">,</FONT>但从语法结构上却不然<FONT face="Times New Roman">.</FONT></P><P 0cm 0pt tab-stops: TEXT-INDENT: mso-list: level1 list -18pt; 45pt; 45.0pt; l67 lfo50?><FONT face="Times New Roman">5. A black-box method by which the interrelation between input and output </FONT>…<FONT face="Times New Roman">plays a fundamental role in operations research.</FONT></P><P 0cm 0pt 45pt?>意思是<FONT face="Times New Roman">:</FONT>黑箱方法不需引进由系统或它的子系统所产生的变换的确切机制而能阐明输入和输出的相互关系<FONT face="Times New Roman">,</FONT>这种方法在运筹学中起了重要的作用<FONT face="Times New Roman">,</FONT>注意这一句中的主语<FONT face="Times New Roman">A black-box and method</FONT>和谓语<FONT face="Times New Roman">plays</FONT>相隔甚远<FONT face="Times New Roman">.</FONT></P><P 0cm 0pt 45pt?><FONT face="Times New Roman"><p></FONT><p> <FONT face="Times New Roman"> </FONT><B><FONT face="Times New Roman"> Exercise </FONT>
</B><P><FONT face="Times New Roman"></FONT></P><P 0cm 0pt?><FONT face="Times New Roman"> </FONT>Ⅰ<FONT face="Times New Roman">. Answer the following questions :</FONT></P><P 0cm 0pt tab-stops: TEXT-INDENT: mso-list: level1 list -18pt; 60.75pt; l36 lfo51?><FONT face="Times New Roman">1. What are the necessary conditions for operation to become an object of scientific approach?</FONT></P><P 0cm 0pt tab-stops: TEXT-INDENT: mso-list: level1 list -18pt; 60.75pt; l36 lfo51?><FONT face="Times New Roman">2. Point out the main points the 2<SUP>nd</SUP> and the 3<SUP>rd</SUP> definitions emphasize as compared with the first definition.</FONT></P><P 0cm 0pt; TEXT-INDENT: 21.75pt?>Ⅱ<FONT face="Times New Roman">. 1. Translate the third definitions of OR due to S. Beer.</FONT></P><P 0cm 0pt tab-stops: TEXT-INDENT: mso-list: level1 list -18pt; 60.75pt; l21 lfo52?><FONT face="Times New Roman">2. Translate the following sentences into Chinese ;</FONT></P><P 0cm 0pt; TEXT-INDENT: 10.5pt? mso-char-indent-count: mso-char-indent-size: -52.5pt; -5.0;><FONT face="Times New Roman"> </FONT>ⅰ<FONT face="Times New Roman">) It was G. Gantor who first introduced the concept of the set as object of mathematical study.</FONT></P><P 0cm 0pt; TEXT-INDENT: 10.5pt? mso-char-indent-count: mso-char-indent-size: -52.5pt; -5.0;><FONT face="Times New Roman"> </FONT>ⅱ<FONT face="Times New Roman">) The definition of probability due to Laplace provoked a great deal of argument when it was applied;</FONT></P><P 0cm 0pt; TEXT-INDENT: 10.5pt? mso-char-indent-count: mso-char-indent-size: -52.5pt; -5.0;><FONT face="Times New Roman"> </FONT>ⅲ<FONT face="Times New Roman">) Nowadays, we usually adopted measure theoretic foundations of probability initiated by A. N. Kolomogorov.</FONT></P><P 0cm 0pt; TEXT-INDENT: 21.75pt?><FONT face="Times New Roman"><p></FONT><p><P 0cm 0pt?><FONT face="Times New Roman"><p></FONT><p><P 0cm 0pt?><FONT face="Times New Roman"><p></FONT><p><P 0cm 0pt?><FONT face="Times New Roman"><p></FONT><p>
数学专业英语[14]-The Theory of Graphs
<b>数学专业英语-The Theory of Graphs</b>
<P><FONT face="Times New Roman" size=3>In this chapter, we shall introduce the concept of a graph and show that graphs can be defined by square matrices and versa.</FONT></P>
<P><FONT face="Times New Roman"><FONT size=3>1.</FONT> <FONT size=3>Introduction</FONT></FONT></P>
<P><FONT face="Times New Roman" size=3>Graph theory is a rapidly growing branch of mathematics. The graphs discussed in this chapter are not the same as the graphs of functions that we studied previously, but a totally different kind. </FONT></P>
<P><FONT size=3><FONT face="Times New Roman"> Like many of the important discoveries and new areas of learning, graph theory also grew out of an interesting physical problem, the so-called Konigsberg bridge problem. (this problem is discussed in Section 2) The outstanding Swiss mathematician, Leonhard Euler (1707-1783) solved the problem in 1736, thus laying the foundation for this branch of mathematics. Accordingly, Euler is called the father of graph theory.</FONT></FONT></P>
<P><FONT size=3><FONT face="Times New Roman"> Gustay Robert Kirchoff (1824-1887), a German physicist, applied graph theory in his study of electrical networks. In1847, he used graphs to solve systems of linear equations arising from electrical networks, thus developing an important class of graphs called trees.</FONT></FONT></P>
<P><FONT size=3><FONT face="Times New Roman"> In 1857, Arthur Caylcy discovered trees while working on differential equations. Later, he used graphs in his study of isomers of saturated hydrocarbons.</FONT></FONT></P>
<P><FONT size=3><FONT face="Times New Roman"> Camille Jordan (1838-1922), a French mathematician, William Rowan Hamilton, and Oystein Ore and Frank Harary, two American mathematicians, are also known for their outstanding contributions to graph theory. </FONT></FONT></P>
<P><FONT size=3><FONT face="Times New Roman"> Graph theory has important applications in chemistry, genetics, management science, Markov chains, physics, psychology, and sociology.</FONT></FONT></P>
<P><FONT size=3><FONT face="Times New Roman"> Throughout this chapter, you will find a very close relationship between graphs and matrices. </FONT></FONT></P>
<P><FONT face="Times New Roman"><FONT size=3>2.</FONT> <FONT size=3>The Konigsberg Bridge Problem</FONT></FONT></P>
<P><FONT face="Times New Roman" size=3>The Russian city of Konigsberg (now Kaliningrad, Russia) lies on the Pregel River.(See Fig.1) It consists of banks A and D of the river and the two islands B and C. There are seven bridges linking the four parts of the city.</FONT></P>
<P><FONT face="Times New Roman"><FONT size=3> Residents of the city used to take evening walks from one section of the city to another and go over some of these bridges. This, naturally, suggested the following interesting problem: can one walk through the city crossing each bridge exactly once? The problem sounds simple, doesn’t it?You might want to try a few paths before going any further. After all, by the fundamental counting principle, the number of possible paths cannot exceed 7!=5040. Nonetheless, it would be time consuming to look at each of them to find one that works.</FONT></FONT></P>
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<P align=center><v:shapetype><v:stroke joinstyle="miter"></v:stroke><v:formulas><v:f eqn="if lineDrawn pixelLineWidth 0"></v:f><v:f eqn="sum @0 1 0"></v:f><v:f eqn="sum 0 0 @1"></v:f><v:f eqn="prod @2 1 2"></v:f><v:f eqn="prod @3 21600 pixelWidth"></v:f><v:f eqn="prod @3 21600 pixelHeight"></v:f><v:f eqn="sum @0 0 1"></v:f><v:f eqn="prod @6 1 2"></v:f><v:f eqn="prod @7 21600 pixelWidth"></v:f><v:f eqn="sum @8 21600 0"></v:f><v:f eqn="prod @7 21600 pixelHeight"></v:f><v:f eqn="sum @10 21600 0"></v:f></v:formulas><v:path extrusionok="f" connecttype="rect" gradientshapeok="t"></v:path><LOCK aspectratio="t" v:ext="edit"></LOCK></v:shapetype><v:shape><v:imagedata><FONT face="Times New Roman" size=3></FONT></v:imagedata></v:shape></P>
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<P align=center><FONT face="Times New Roman" size=3>Fig .1 The city of Konigsberg</FONT></P>
<P><FONT face="Times New Roman" size=3>In 1736, Euler proved that no such walk is possible. In fact, he proved a far more general theorem, of which the Konigsberg bridge problem is a special case. </FONT></P>
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<P align=center><FONT face="Times New Roman" size=3>Fig .2 A mathematical model for the Konigsberg bridge problem</FONT></P>
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<P><FONT size=3><FONT face="Times New Roman"> Let us construct a mathematical model for this problem.rcplace each area of the city by a point in a plane. The points A, B, C,and D denote the areas they represent and are called vertices. The arcs or lines joining these points represent the represent the respective bridges. (See</FONT>图2<FONT face="Times New Roman">)They are called edges. The Konigsberg bridge problem can now be stated as follows: Is it possible to trace this figure without lifting your pencil from paper or going over the same edge twice? Euler proved that a figure like this can be traced without lifting pencil and without traversing the same edge twice if and only if it has no more than weo vertices with an odd number of edges joining them. Observe that more than two vertices in the figure have an odd number of edges connecting them-----in fact,they all do.</FONT></FONT></P> <P 0cm 0pt tab-stops: TEXT-INDENT: mso-list: level1 list 18.0pt; 18pt; -18pt; l41 lfo53?><FONT face="Times New Roman">1. Graphs</FONT></P><P 0cm 0pt?><FONT face="Times New Roman">Let us return to the example Friendly Airlines flies to the five cities, Boston (B), Chicago (C), Detroit (D), Eden (E), and Fairyland (F) as follows: it has direct daily flights from city B to cities C, D, and F, from C to B, D, and E; from D to B, C, and F, from E to C, and from F to B and D. This information, though it sounds complicated, can be conveniently represented geometrically, as in </FONT>图<FONT face="Times New Roman">3. Each city is represented by a heavy dot in the figure; an arc or a line segment between two dots indicates that there is a direct flight between these cities.</FONT></P><P 0cm 0pt?><v:shapetype><v:stroke joinstyle="miter"></v:stroke><v:formulas><v:f eqn="if lineDrawn pixelLineWidth 0"></v:f><v:f eqn="sum @0 1 0"></v:f><v:f eqn="sum 0 0 @1"></v:f><v:f eqn="prod @2 1 2"></v:f><v:f eqn="prod @3 21600 pixelWidth"></v:f><v:f eqn="prod @3 21600 pixelHeight"></v:f><v:f eqn="sum @0 0 1"></v:f><v:f eqn="prod @6 1 2"></v:f><v:f eqn="prod @7 21600 pixelWidth"></v:f><v:f eqn="sum @8 21600 0"></v:f><v:f eqn="prod @7 21600 pixelHeight"></v:f><v:f eqn="sum @10 21600 0"></v:f></v:formulas><v:path extrusionok="f" connecttype="rect" gradientshapeok="t"></v:path><LOCK aspectratio="t" v:ext="edit"></LOCK></v:shapetype><v:shape><FONT face="Times New Roman"><v:imagedata></v:imagedata><v:textbox style="mso-next-textbox: #_x0000_s1026"></v:textbox><w:wrap type="tight"></w:wrap></FONT></v:shape><FONT face="Times New Roman"> What does this figure have in common with </FONT>图2<FONT face="Times New Roman">? Both consist of points (denoted by thick dots ) connected by arcs or line segments. Such a figure is called a graph. The points are the vertices of the graph; the arcs and line segments are its edges. More generally, we make the following definition:</FONT></P><P 0cm 0pt; TEXT-INDENT: 21.75pt?><FONT face="Times New Roman">A graph consists of a finite set of points, together with arcs or line segments connecting some of them. These points are called the vertices of the graph; the arcs and line segments are called the edges og the graph. The vertices of graph are usually denoted by the letters A, B, C, and so on. An edge joining the vertices A and B is denoted by AB or A-B.</FONT></P><P 0cm 0pt; TEXT-INDENT: 10.5pt? mso-char-indent-count: mso-char-indent-size: 336pt; 32.0;><FONT face="Times New Roman">Fig .3</FONT></P><P 0cm 0pt?><FONT face="Times New Roman"> </FONT>图2<FONT face="Times New Roman">and </FONT>图<FONT face="Times New Roman">3 are graphs. Other graphs are shown in </FONT>图<FONT face="Times New Roman">4. The graph in</FONT>图2<FONT face="Times New Roman"> has four vertices A, B, C, and D, and seven edges AB, AB, AC, BC, BD, CD, and BD. For the graph in</FONT>图<FONT face="Times New Roman">4b, there are four vertices, A, B, C, and D, but only two edges AD and CD. Consider the graph in</FONT>图<FONT face="Times New Roman">4c, it contains an edge emanating from and terminating at the same vertex A. Such an edge is called a loop. The graph in</FONT>图<FONT face="Times New Roman">4d contains two edges between the vertices A and C and a loop at the vertex C. </FONT></P><P 0cm 0pt?><FONT face="Times New Roman"> </FONT><v:shape><v:imagedata></v:imagedata></v:shape><FONT face="Times New Roman"> </FONT></P><P 0cm 0pt; TEXT-INDENT: 10.5pt? mso-char-indent-count: mso-char-indent-size: 10.5pt; 1.0;><FONT face="Times New Roman">
</FONT><p><P 0cm 0pt; TEXT-INDENT: 10.5pt? mso-char-indent-count: mso-char-indent-size: 10.5pt; 1.0;><FONT face="Times New Roman">The number of edges meeting at a vertex A is called the valence or degree of the vertex, denoted by v(A). For the graph in</FONT>图<FONT face="Times New Roman">4b, we have v(A)=1, v(B)=0, v(C)=1, and v(D)=2. In</FONT>图<FONT face="Times New Roman">4b, we have v(A)=3, v(B)=2, and v(C)=4.</FONT></P><P 0cm 0pt?><FONT face="Times New Roman"> A graph can conveniently be described by using a square matrix in which the entry that belong to the row headed by X and the column by Y gives the number of edges from vertex X to vertex Y. This matrix is called the matrix representation of the graph; it is usually denoted by the letter M.</FONT></P><P 0cm 0pt?><FONT face="Times New Roman"> The matrix representation of the graph for the Konigsberg problem is </FONT></P><P 0cm 0pt?><FONT face="Times New Roman"> </FONT><v:shape><v:imagedata></v:imagedata></v:shape></P><P 0cm 0pt?><FONT face="Times New Roman">Clearly the sum of the entries in each row gives the valence of the corresponding vertex. We have v(A)=3, v(B)=5, v(C)=3, as we would expect.</FONT></P><P 0cm 0pt?><FONT face="Times New Roman"> Conversely, every symmetric square matrix with nonnegative integral entries can be considered the matrix representation of some graph. For example, consider the matrix </FONT></P><P 0cm 0pt?><FONT face="Times New Roman"> A B C D </FONT></P><P 0cm 0pt?><v:shape><v:imagedata><FONT face="Times New Roman"></FONT></v:imagedata></v:shape></P><P 0cm 0pt?><FONT face="Times New Roman">Clearly, this is the matrix representation of the graph in </FONT>图<FONT face="Times New Roman">5.</FONT></P>