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1.
物理问题中的很大一部分内容属于非线性方程,求解这类问题用数学公式很难求解出解析解,特别是代数方程中的方次n4时,是不可能用代数方法求解的,只能求出数值解。随着计算机的发展,应用计算机的大存储量和快速计算,对物理问题进行科学计算和数值模拟近年来得到很大发展,通过C语言对几个物理问题的求解,展示计算机在物理问题解决过程的作用。 相似文献
2.
《实验室研究与探索》2020,(8)
通过发射线圈发射一次场,计算空间中磁场的分布情况进而获得金属目标激发二次场的强弱。结合实际工作状态下天线经过金属目标物正上方时所得信号的波形特点,提出了一种具有高匹配度的滤波函数模型。使用该滤波函数提出了一种快速高效的匹配滤波方法,经过累加、平均、插值等计算,对采集的二次场特征值进行处理,分析其能量分布,最终完成目标物的识别和定位。经现场实验验证,所使用的滤波方法可以快速处理大量数据,实现对目标物的判别和精确定位,符合浅地表电磁探测实际工程的要求。 相似文献
3.
高中物理第一册 (必修 )课本在“测定匀变速直线运动的加速度”的学生实验中 ,要求学生用逐差法计算匀速直线运动的加速度 :由测得的各段位移ｓ1,ｓ2 ,…求出ａ1=(ｓ4 -ｓ1) /3Ｔ2 ,ａ2 =(ｓ5-ｓ2 ) /3Ｔ2 …再算出ａ1,ａ2 ,…的平均值 ,就是我们所要测定的匀变速直线运动的加速度 .1 逐差法教学改进的必要性逐差法的优点是 :尽可能多地利用实验数据 ,减小了偶然误差 ,使测得的结果更好地接近真实值 ,缺点是计算量大 ,费时 .尤其是在学生参加全国高考时 ,时间紧 ,任务重 ,又不允许使用电脑和计算器 ,在这种情况下 ,大量的数值计算令人心烦… 相似文献
4.
本文介绍某些数列求和的一种方法:把数列各项转化为几何图形(线段,正三角形、正四面体)上的点,把图形作适当旋转(一次、两次或更多次,旋转180°或120°),再把所得图形重叠起来,使各点上的数都相等,然后计算点的个数,即可求出数列的和。 相似文献
5.
提出了一种不修改通用有限元程序建立的随机有限元方法，即计算机随机产生多组零件尺寸，用通用有限元软件对每组数据进行计算，求出零件危险截面应力等。对应力数据进行检验，若应力服从正态分布、指教分布、威布尔分布、对教正态分布中任一种，强度可靠度可通过公式或数值积分得到。若应力分布不确定，则可靠度用Monte Carlo法求出。变形的可靠度用同样方法解决。用该方法编写的计算机程序，使形状复杂零件的可靠度计算成为可能。 相似文献
6.
7.
常规的曝气设备充氧性能实验中K La测定需要作图及大量的计算,花费大量的人工,需要一段时间后才能求出K La。本文将通过计算机数据采集的方法,自动记录溶解氧数据,再由计算机非线性回归的方法进行拟合计算。与传统的方法相比,计算机自动数据采集的方法除了可以避免手工数据记录误差、测定快速之外;还能够对实验数据进行快速分析判断,对可能的导致实验误差或错误的问题进行诊断。 相似文献
8.
行株距配置对夏玉米产量及田间小气候的影响 总被引：2，自引：0，他引：2
以玉米隆平206为试验材料,设行距为50cm、60cm、70cm、80cm的四种种植方式,研究了不同行株距配置对夏玉米产量及田间小气候的影响。结果表明,行距对产量有显著影响,行距为50cm时产量最高,行距对田间小气候下的日平均温度、相对湿度、日平均光强、日平均风速有显著影响,随着行距增大日平均温度和相对湿度逐渐减小,日平均光强和日平均风速逐渐增大。各气候因子对产量的影响不同,相对湿度和产量的关联度最大,对产量影响最大。50cm行距配置可有效协调群体内各气候因子之间的矛盾,产量最高。 相似文献
9.
实验用14日龄AA肉鸡40只,等分成1、2、3、4组,分别口服接种熏蒸12、24、36h和未经熏蒸处理的柔嫩艾美球虫卵囊10×104个,并于接种后第8天称重,追杀,检查病变、OPG,计算耗料、饲料转化率、平均日增重、卵囊值及病变记分。结果表明第1、4组球虫症状明显,各项指标均次于2、3组,但各组鸡OPG均较高,熏蒸消毒对柔嫩艾美球虫致病力基本上无影响． 相似文献
10.
通过实验研究物理规律时,必须对定量测量各物理量所得的实验数据加以分析处理,从中找出要研究或检验的物理规律,或求出有关物理量的实验结果.处理数据的方法有多种,作图法就是其中之一. 相似文献
11.
C. O. Neidt D. D. Sjogren 《Educational technology research and development : ETR & D》1968,16(3):268-279
Summary Scales measuring attitude toward a course were administered five times at equally spaced intervals throughout the course to
college students. The students were in courses taught by one of four methods of instruction; programed, television, small
class, and large class. The mean scores on the attitude scales differed significantly among the methods of instruction on
each of the five administrations. The means of the methods were consistently ordered as follows: programed instruction television
instruction > small class > large class. There was also a consistent decline in the mean scores over the five administrations.
Novelty of the method for the students was offered as the variable differentiating the methods associated with the attitudinal
differences. Other hypotheses were also discussed.
The research reported here was one of several projects performed pursuant to a contract with the Office of Education, United
States Department of Health, Education, and Welfare. 相似文献
12.
Sap flow and environmental conditions were monitored at two Eucalyptus (Eucalyptus urophylla S.T.Blake)plantations at Hetou and Jijia, located in Leizhou, Zhanjiang, Guangdong Province. It was found that daily sap flux density (SFD) of Eucalyptus was closely related to daily atmospheric vapor pressure deficit (VPD) (R2=0.76, P=0.01 at Hetou and R2=0.7021, P=0.01 at Jijia) at both sites. No significant relationship existed between daily SFD and mean daily air temperature at both sites. Daily SFD varied with wind speed Y=-17585X3 15147X2-1250.7X 2278.4 (R2=0.68; P=0.01) at Hetou and Y=-101.67X3-1.65X2-376.4X 1914.8 (R2=0.40, P=0.05) at Jijia, where Ywas daily SFD, Xwas daily wind speed.Experimental observations yielded the following data: (1) the critical lower and upper daily VPD threshold were 0 and 2 kPa,slightly lower under high relative humidity (＞80%) compared with those at the Jijia site; (3) The upper and lower threshold 相似文献
13.
Residence time is an important indicator for river environmental management. In this paper, a 3D hydrody-namic model has been successfully applied to Little Manatee River to characterize the mixing and transport process and residence time. The model employs horizontal curvilinear orthogonal grids to represent the complex river system that consists of branches and bayous. The model has been satisfactorily calibrated and verified by using two continuous data sets. The data sets consist of hourly observations of all forcing boundaries, including freshwater inputs, tides, winds, salin-ity and temperatures at bay boundary, and air temperatures for model simulations. The data sets also consist of hourly observations of water levels, salinity, and temperature at several river stations. The calibrated and verified hydrodynamic model was used to predict residence time in the Little Manatee River. Under the minimum flow of 0.312 m3/s, the pulse residence time (PRT) is 108 days. Model simulations were also conducted for 17 flow scenarios. Empirical regression equations have been satisfactorily derived to correlate PRT to freshwater inflow. Correlation coefficient R2 is 0.982 for PRT. 相似文献
14.
Sarah E. Swehla Matthew K. Burns Anne F. Zaslofsky Matthew S. Hall Sashank Varma Robert J. Volpe 《Psychology in the schools》2016,53(4):404-415
Incremental rehearsal (IR) is a highly effective intervention that uses high repetition and a high ratio of known to unknown items with linearly spaced known items between the new items. It has been hypothesized that narrowly spaced practice would result in quick learning, whereas items that are widely spaced would result in longer‐term retention. The current study examined the effect of spacing by teaching vocabulary words to 36 fourth‐grade students. Each student was randomly assigned to a widely spaced IR condition (i.e., one unknown item, one known item, one unknown item, two known items, one unknown item, three known items, and an increase in the number of known items presented each time by one) or an IR condition in which spacing increased exponentially (IR‐Exp; i.e., one unknown item, one known item, one unknown item, two known items, one unknown item, four known items, and one unknown item, eight known items). The results indicated that the students in the study retained twice as much information with the widely spaced IR than with the IR‐Exp condition, but the latter required half as much time. IR and IR‐Exp were equally efficient, but IR continues to be superior to all other flashcard approaches in improving retention. 相似文献
15.
选取四川盆地19个地面气象站1961～2000年气温（平均气温、最高气温和最低气温）的逐日观测资料,运用最小二乘法计算气候倾向率和年代际变化的方法,对近40年来四川盆地气温的季节、年际和年代际变化进行了诊断分析,结果表明：（1）从年平均气温来看,三种气温的年平均值,四川盆地都以增温的趋势为主,增幅分别是0.027℃/10a、0.007℃/10a和0.036℃/10a,最低气温增幅大于最高气温.（2）在20世纪60、70年代气温逐渐降低,80年代是气温的低值区,80年代后期气温逐渐升高,90年代升温明显;而降水60、70年代降水量较多,但已经出现了逐渐减少的变化趋势,80年代至90年代降水量减少.（3）从季平均气温来看,春夏季三种气温呈下降趋势,其中季平均气温的下降幅度最大为-0.08℃/10a;秋冬季三种气温呈上升趋势,其中季平均最高气温的增幅最大为0.15℃/10a. 相似文献
16.
通过改进四个三阶收敛的Newton迭代法得到一些新的方法来解非线性方程,并证明这些方法具有五阶收敛性.然后通过数值实例对文中的新方法和原来的三阶收敛迭代法进行比较,说明本文方法的有效性. 相似文献
17.
长江流域近40年平均地温时空变化分析 总被引：2，自引：0，他引：2
选取长江流域107个测站1961～2000年逐日平均地温资料（0㎝）,利用最小二乘法通过计算气候倾向率和年代际变化的方法,对长江流域年、季平均地温的时空分布和变化特征进行了研究。认为：（1）从年均地温来看,上、下游的地温升高,下游升幅大于上游,中游基本无变化。（2）从季节来看,春季上游地温降低,中、下游地温升高,下游升幅大于中游 夏季整个长江流域地温都降低,其中下游降幅最大,为-0.427℃/10a 而与夏季相反,冬秋两季,长江流域地温升高。 相似文献
18.
《家用空气源热泵辅助型太阳能热水系统技术条件》中对整机综合制热性能系数（COP）试验的平均环境温度和全天太阳能辐照量给出了一定变化范围,为研究这一变化对整机综合COP的影响,将整机的性能试验分两个阶段进行,其中太阳能热水系统加热段在户外进行,空气源热泵加热段在环境温度可控的环境试验室进行。试验表明在标准规定的变化范围内,平均环境温度的变化及全天辐照量的变化对空气源热泵辅助太阳能热水系统整机综合COP有较大影响．其中因平均环境温度的变化及全天辐照量的变化对太阳能热水系统性能影响而引起整机综合COP的变化较小．而因平均环境温度的变化对空气源热泵性能的影响而引起整机综合COP的变化最大可达40％左右。据此对该标准的试验方法、试验条件提出了修改建议。 相似文献
19.
分析了4类风口模型（即基本模型、盒子模型、N点动量模型、主流区风口模型）在计算流体动力学中的应用以及在实际工程案例中的运行情况.在环境舱内进行了足尺实验,利用全方位热风速表测量了环境舱内的气流速度和温度场,并与4类风口模型的模拟结果进行比较.结果表明：基本模型与盒子模型并不适用于结构复杂的送风口模拟;基于N点动量模型和主流区风口模型的流体速度在工作区的模拟值与实测值的相对误差小于20%;在主流区风口模型中,送风口附近的气体速度模拟值与实测值的最大相对误差小于15%.证明主流区风口模型相对于其他3类风口模型而言,对于结构复杂的送风口模拟更准确,应用性更强. 相似文献
20.
Xiao-jun Ma Xu-guang Jiang Yu-qi Jin Hong-mei Liu Xiao-dong Li Tong Chen Jian-hua Yan 《浙江大学学报(A卷英文版)》2012,13(1):69-78
The emission of dioxins from municipal solid waste incinerators (MSWIs) has become a widespread concern. The effect of meteorological
parameters (wind speed, atmospheric stability and mixing height) on the hourly ground level concentration (GLC) of dioxins
was estimated using air dispersion models. Moreover, the health risks of dioxin exposure were evaluated for children and adults
using the Nouwen equation. The total environmental exposure via air inhalation and food ingestion was calculated, based on
linear fit equations. The results indicate that potentially severe pollution from dioxins occurs at a wind speed of 1.5 m/s
with atmospheric stability class F. In addition, local residents in the study area are exposed to severe weather conditions
most of the time, and the risk exposures for children are far higher than those for adults. The total exposure for children
far exceeds the tolerable daily intake of dioxin recommended by the World Health Organization (WHO) of 1–4 pg TEQ/(kg·d) under
severe weather conditions. Results from modeling calculations of health risk assessment were consistent with dioxin levels
obtained during actual monitoring of emissions. 相似文献