内差法在电线电缆结构计算中的应用

内差法是工程上运用较为广泛的一种计算方法。它的优点是:计算简单,精确度较高,而且精确度能通过本身计算控制。

迭代法在辐射仪表标定中的应用

本文在以往用线性内差法校准总辐射表、散射辐射表的基础上,阐述了应用迭代法进行辐射仪表的标定以及有关的计算方法,并得出了一些初步的结果。

改进的灰色关联分析方法在水质评价中的应用研究

为了比较清晰分级河段水质,采用灰色关联分析法对河段水质进行了评价,应用分段线形法对样本进行了归一化处理,并在原有公式基础上进行了改进,针对关联分析法分辨率较低的问题,采用了级别内插法来提高灰色关联评价法的分辨率。以清河干流为例,分析得出了清河干流2010年水质级别为1.8,0.4,0.5。

几种特殊面的预裂爆破方法

在预裂爆破中,平直面预裂是经常遇到的一种情况,从设计到钻孔施工,一般较容易进行。但偶尔也会遇到一些特殊面要求预裂,其复杂性也显而易见。1 不同坡比的折面无论对于成锐角或钝角的折面,其难点都在于两面相交折角处交线的钻孔参数的确定和折角两侧预裂孔深度的计算。如图1,其坡比分别为 m 和 n 的两坡面以锐角∠BAC 相交,AE 为两面交线,A、B、C 三点为放线所需的已知点,D、E 两点高程为已知的钻孔顶、底高程,BD与 CD 的交点 D 可以通过放线找出来。则两交线 AE的长度和倾角为:

低空摄影测量在弹丸落点坐标测试中的应用

靶场现有落点坐标测试设备大多数基于地面观测平台,存在通视要求的局限性,无法及时预测落点概略坐标,且对于连发密集型射击试验无法区分弹序。针对该问题,根据物点与像点的几何位置关系,提出了3种将观测平台设置为空中的无人机弹丸落点测量方法:内差法、距离比例法以及求解姿态角法。介绍了3种算法的基本原理和数学模型,然后结合模拟试验现场的测试数据对3种方法进行了验证,最后计算出满足要求所需要的相机最低技术指标。实验结果表明:内差法和比例法测量精度低于3m,求解姿态角法的精度小于0.3m。

光栅传感器在油泵试验台喷油量测控中的应用

对光栅传感器输出的两个相差 90°的莫尔信号 ,用内差法进行细分 (倍频 )。使其在莫尔信号变化的一个周期内 ,输出 10个均匀分布的计数脉冲 ,并用计数器对之进行计数 ,从而实现了喷油泵喷油量的测量与控制。实际应用表明 ,用此方法进行测量 ,试验台工作稳定 ,抗干扰性强 ,精度大为提高。

A numerical study of fracture initiation under different loads during hydraulic fracturing

The fracture initiation behavior for hydraulic fracturing treatments highlighted the necessity of proposing fracture criteria that precisely predict the fracture initiation type and location during the hydraulic fracturing process.In the present study,a Mohr-Coulomb criterion with a tensile cut-off is incorporated into the finite element code to determine the fracture initiation type and location during the hydraulic fracturing process.This fracture criterion considers the effect of fracture inclination angle,the internal friction angle and the loading conditions on the distribution of stress field around the fracture tip.The results indicate that the internal friction angle resists the shear fracture initiation.Moreover,as the internal friction angle increases,greater external loads are required to maintain the hydraulic fracture extension.Due to the increased pressure of the injected water,the tensile fracture ultimately determines the fracture initiation type.However,the shear fracture preferentially occurs as the stress anisotropy coefficient increases.Both the maximum tensile stress and equivalent maximum shear stress decrease as the stress anisotropy coefficient increases,which indicates that the greater the stress anisotropy coefficient,the higher the external loading required to propagate a new fracture.The numerical results obtained in this paper provide theoretical supports for establishing basis on investigating of the hydraulic fracturing characteristics under different conditions.

Intracellular temperature measurement by a dual-thermocouple difference method

A dual thermocouple difference technique is developed to determine the accuracy and anti-interference ability in the process of intracellular temperature measurement.First,two micro-nano thermocouples(TC)and a high-precision signal acquisition module are used to measure the temperature difference between the cell and the culture medium(separated about 10μm from the cell).The cold junctions of two TCs are connected to eliminate the setting of the reference temperature and enhance the anti-interference ability.Then,a low-noise voltage amplifier and digital acquisition card are used to sample signals.In order to verify the feasibility of the dual thermocouple difference method,the temperature changes of U251 cells are detected.The calibration results of two TCs show that the Seebeck coefficient is about 5μV/℃,and the signal acquisition accuracy is 0.5μV in a low voltage range(0-15μV).With the dual thermocouple difference method,errors due to the cold junctions can be removed and the interference caused by environmental temperature fluctuation can be reduced.The phenomenon of cellular temperature increase proves that the dual thermocouple difference method can detect the tiny temperature change of a single cell.The method potentially is a highly powerful technique for studying local thermogenesis of cells and helps to explore the relationship between cellular thermogenesis and cellular processes.

Fast Residual Quad-Tree Coding for the Emerging High Efficiency Video Coding Standard

In High Efficiency Video Coding, the Residual Quad-Yree （RQT） coding is used to encode the prediction residual for both intra and inter Coding Units （CU） and provides improved coding gains. However, this results in much higher computational complexities. To address this problem, we develop two fast RQT algorithms for intra- and inter-prediction residual coding respectively. For intra coding, the proposed algorithm selects the best prediction mode in the rate distortion mode decision process using a Prediction Unit （PU） size-dependent fast RQT depth decision on a reduced prediction mode candidates set from the rough mode decision process. For inter coding, in addition to CU size-dependent fast RQT depth decisions, we propose a discriminant analy- sis-based fast depth decision algorithm to det- ermine the best transform unit size. Experimental results show that on average, we can real- ise a 21.29% encoding time saving and 0.03% bit-rate reduction for intra coding, while 15% of the encoding time can be saved with a negligible coding performance loss for inter coding.

A Predictive Nighttime Ventilation Algorithm to Reduce Energy Use and Peak Demand in an Office Building

The effect of two nighttime ventilation strategies on cooling and heating energy use is investigated for a prototype office building in several northern America climates, using hourly building energy simulation software （DOE2.1E）. The strategies include： scheduled-driven nighttime ventilation and a predictive method for nighttime ventilation. The maximum possible energy savings and peak demand reduction in each climate is analyzed as a function of ventilation rate, indoor-outdoor temperature difference, and building thermal mass. The results show that nighttime ventilation could save up to 32% cooling energy in an office building, while the total energy and peak demand savings for the fan and cooling is about 13% and 10%, respectively. Consequently, finding the optimal control parameters for the nighttime ventilation strategies is very important. The performance of the two strategies varies in different climates. The predictive nighttime ventilation worked better in weather conditions with fairly smooth transition from heating to cooling season.

Autonomous Kernel Based Models for Short-Term Load Forecasting

The application of support vector machines to forecasting problems is becoming popular, lately. Several comparisons between neural networks trained with error backpropagation and support vector machines have shown advantage for the latter in different domains of application. However, some difficulties still deteriorate the performance of the support vector machines. The main one is related to the setting of the hyperparameters involved in their training. Techniques based on meta-heuristics have been employed to determine appropriate values for those hyperparameters. However, because of the high noneonvexity of this estimation problem, which makes the search for a good solution very hard, an approach based on Bayesian inference, called relevance vector machine, has been proposed more recently. The present paper aims at investigating the suitability of this new approach to the short-term load forecasting problem.

Multi-responsive red solid emitter: Detection of trace water and sense of relative humidity

A multi-responsive D-A type compound(CYQ)based on pyrone and triphenylamine was designed and successfully synthesized. The target compound exhibited distinct aggregation-enhanced emission(AEE) effect.Solvatochromic experiment and density functional theory(DFT) indicated CYQ possessed excellent intramolecular charge transfer(ICT) ability. Besides, its mechanofluorochromic property(MFC) was found with a 37 nm redshift. Powder wide-angle X-ray diffraction(PXRD) and differential scanning calorimetry(DSC) measurements were performed to demonstrate the transformation from the crystalline to amorphous states upon grinding. Surprisingly,CYQ displayed a hypersensitive response to trace water in organic solvents with an excellent detection limit as low as 0.0096% in tetrahydrofuran(THF). Furthermore, it was found that the fluorescent intensity of CYQ declined progressively upon humidity rise, and its color change can be witnessed by naked eyes. Therefore, the relative humidity(RH) sensing strategy guarantees the AIEgen to become a colorimetric sensor under various conditions.