提高直流单电桥测电阻准确度的讨论

直流单电桥主要用来测量1～10^6Ω中阻值电阻，它的特点是灵敏度高，可获得高精度的测量结果。尽管直流单电桥的灵敏度高，我们能否进一步提高其灵敏度，得到更为准确的被测电阻阻值呢?本文从理论上论证找到了灵敏度与哪些因素有关，从而找到了提高直流单电桥测电阻准确度的各种方法。     

惠斯登电桥灵敏度与测量精度的探究

介绍了惠斯登电桥测量电阻的原理,通过实验数据验证了影响惠斯登电桥测量精度的因素.主要有电桥灵敏度及桥臂电阻的误差两个方面,电桥的灵敏度与电源电压、检流计、桥臂总阻值有关.推导出电桥灵敏度与比例臂电阻取值的极值条件.指出进行换臂测量能够消除由比例臂R1和R2带来的相对误差,提高测量精度.     

单臂电桥电阻搭配对测量灵敏度的影响

讨论用直流单臂电桥测量电阻时，四个臂电阻如何搭配能提高测量灵敏度．     

惠斯通电桥灵敏度的实验研究

惠斯通电桥的灵敏度是影响其测量精确度的一个重要因素．文章对惠斯通电桥的灵敏度进行实验研究．通过惠斯通电桥测电阻实验,获得了大量的实验数据,并给出电桥灵敏度Smax与比例臂r的关系．结果表明：电桥灵敏度Smax的增大随比例系数r而增大．这为用惠斯通电桥测电阻的选取实验参数、提高电阻的测量精度和获取最大灵敏度提供了依据,从而具有参考价值和可操作性．     

惠斯通电桥最大灵敏度的仿真分析

惠斯通电桥灵敏度是影响惠斯通电桥测量精度的重要因素之一.通过MATLAB仿真实验,结果表明,电桥的灵敏度与比例系数Kp、电阻R2、及被测电阻Rx成多参数非线性关系.若使电桥始终保持较高测量精度,应使Kp和R（2即R1、R2和R3）随外接元件等效电阻Rx的大小进行非线性调节.     

测电阻实验中不确定度的研究

惠斯登直流电桥测电阻是常用的测电阻方法,主要是通过电桥的平衡原理来进行实验。本实验主要通过电桥的灵敏域/灵敏度、检流计电流、电压与比例四个方面对实验中所产生的不确定度进行研究,总结出测量电阻最佳的条件,提高测量精度,促进教学。     

单电桥的灵敏度及测量误差

用两种不同方法导出了单电桥的相对灵敏度计算公式，分析了影响相对灵敏度的各种因素.并在此基础上讨论了滑线电桥的灵敏度及其对所测电阻Rx的影响，从理论上给出了滑线电桥最小相对误差的条件要使滑线电桥灵敏度所引起的相对误差最小，电桥平衡点的位置应按待测电阻Rx与检流计内阻Rg的比值来确定.从而，为实验时通过选择最佳桥臂比N来减小测量误差提供了理论依据.     

用非平衡单臂电桥测量金属丝杨氏弹性模量

用非平衡单臂电桥测量金属丝杨氏弹性模量张引科，王兆凤（西安建筑科技大学物理实验教研室，陕西省轻工业学校，西安７１００１６；第一作者，男，３０岁，讲师）单臂电桥（惠斯顿电桥）是测量电阻的常用设备．通过调节电桥平衡，可以精确测量电阻的大小．但是，如果电阻...     

用调节电阻补偿法消除多维力测量中向间干扰

介绍一种消除各分力之间相互干扰的新方法－调节电阻补偿法，其特点是通过联接适当的调节电阻，改变某或某几个应变片的输出灵敏度，从而在测量电桥内部完全消除各分力之间的干扰。     

双电桥桥臂电阻对电桥灵敏度的影响

通过与单电桥相比,得出双电桥桥臂电阻与电桥灵敏度的关系,从而确定了双电桥桥臂电阻选择的原则     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

橡胶颗粒沥青混合料低温抗裂性试验研究

以AC-13级配为基础,将橡胶颗粒代替部分集料掺入混合料中,以低温弯曲试验为评价方法对不同橡胶颗粒掺量下沥青混合料的低温抗裂性进行研究,并引入应变能密度值对混合料的低温抗裂性进行综合评价.试验结果表明:橡胶颗粒沥青混合料试件的破坏微应变均超过2 300,满足冬寒区的技术指标;无论是否掺加橡胶颗粒,随着温度的下降,沥青混合料破坏时的最大弯拉强度增大,弯拉应变降低,劲度模量增大;弯曲应变能密度在胶粒掺量为1%左右时具有较大的弯曲应变能密度值,此时橡胶颗粒沥青混合料具有较好的低温抗裂性.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

Quantitative trait loci （QTLs） for quality traits related to protein and starch in wheat

Quality traits in wheat （Triticum aestirum L.） were studied by quantitative trait locus （QTL） analysis in a recombinant inbred line （RIL） population, a set of 131 lines derived from Chuan 35050 × Shannong 483 cross （ChSh）. Grains from RILs were assayed for 21 quality traits related to protein and starch. A total of 35 putative QTLs for 19 traits with a single QTL explaining 7.99-40.52% of phenotypic variations were detected on 10 chromosomes, 1D, 2A, 2D, 3B, 3D, 5A, 6A, 6B, 6D, and 7B. The additive effects of 30 QTLs were positive, contributed by Chuan 35050, the remaining 5 QTLs were negative with the additive effect contributed by Shannong 483. For protein traits, 15 QTLs were obtained and most of them were located on chromosomes 1 D, 3B and 6D, while 20 QTLs for starch traits were detected and most of them were located on chromosomes 3D, 6B and 7B. Only 7 QTLs for protein and starch traits were co-located in three regions on chromosomes 1D, 2A and 2D. These protein and starch trait QTLs showed a distinct distribution pattern in certain regions and chromosomes. Twenty-two QTLs were clustered in 6 regions of 5 chromosomes. Two QTL clusters for protein traits were located on chromosomes 1D and 3B, respectively, three clusters for starch traits on chromosomes 3D, 6B and 7B, and one cluster including protein and starch traits on chromosome 1D.     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.