Longitudinal dispersion with constant source concentration along unsteady groundwater flow in finite aquifer: analytical solution with pulse type boundary condition

Analytical solution is obtained to predict the contaminant concentration with presence and absence of pollution source in finite aquifer subject to constant point source concentration. A longitudinal dispersion along unsteady groundwater flow in homogeneous and finite aquifer is considered which is initially solute free that is, aquifer is supposed to be clean. The constant source concentration in intermediate portion of the aquifer system is considered with pulse type boundary condition and at the other end of the aquifer, concentration gradient is supposed to be zero. The Laplace Transformation Technique (LTT) is used to obtain the analytical solution of the formulated solute transport model with suitable initial and boundary conditions. The time varying velocities are considered. Analytical solutions are perhaps most useful for benchmarking the numerical codes and models. It may be used as the preliminary predictive tools for groundwater management.

Multi-Deployment of Dispersed Power Sources Using RBF Neural Network

Multi-deployment of dispersed power sources became an important need with the rapid increase of the Distributed generation (DG) technology and smart grid applications. This paper proposes a computational tool to assess the optimal DG size and deployment for more than one unit, taking the minimum losses and voltage profile as objective functions. A technique called radial basis function (RBF) neural network has been utilized for such target. The method is only depending on the training process;so it is simple in terms of algorithm and structure and it has fast computational speed and high accuracy;therefore it is flexible and reliable to be tested in different target scenarios. The proposed method is designed to find the best solution of multi- DG sizing and deployment in 33-bus IEEE distribution system and create the suitable topology of the system in the presence of DG. Some important results for DG deployment and discussion are involved to show the effectiveness of our proposed method.

Designing the cooling system of a hybrid electric vehicle with multi-heat source

In order to reduce the power consumption and meet the cooling demand of every heat source component, three kinds of multi-heat source cooling system schemes were designed base on the characteristic of power split hybrid electric vehicle （HEV）. Using the numerical simulation meth- od, the power system heat transfer model was built. By comparing the performance of three differ- ent schemes through the Simulink simulation, the best cooling system scheme was found. Base on characteristics of these cooling system structures, the reasonableness of the simulation results were analyzed and verified. The results showed that the cooling system designation based on the numerical simulation could describe the cooling system performance accurately. This method could simplify the design process, improve design efficiency and provide a new way for designing a multi-heat source vehicle cooling system.

Application of passive source surface-wave method in site engineering seismic survey

Site engineering seismic survey provides basic data for seismic effect analysis. As an important parameter of soil, shear-wave velocity is usually obtained through wave velocity testing in borehole. In this paper, the passive source surface-wave method is introduced into the site engineering seismic survey and practically applied in an engineering site of Shijingshan District. By recording the ubiquitous weak vibration on the earth surface, extract the dispersion curve from the surface-wave components using the SPAC method and obtain the shear-wave velocity structure from inversion. Over the depth of 42 m under- ground, it totally consists of five layers with interface depth of 3.31, 4.50, 7.23, 17.41, and 42.00 m; and shear-wave velocity of 144.0, 198.3, 339.4, 744.2, and 903.7 m/s, respectively. The inversion result is used to evaluate site classification, determine the maximum shear modulus of soil, provide basis for further seismic hazard analysis and site assessment or site zoning, etc. The result shows that the passive source surface-wave method is feasible in the site engineering seismic survey and can replace boreholes,shorten survey period, and reduce engineering cost to some extent.

One Dimensional Solute Transport Originating from a Exponentially Decay Type Point Source Along Unsteady Flow Through Heterogeneous Medium

One dimensional advection dispersion equation is analytically solved initially in solute free domain by considering uniform exponential decay input condition at origin. Heterogeneous medium of semi infinite extent is considered. Due to heterogeneity velocity and dispersivity coefficient of the advection dispersion equation are considered functions of space variable and time variable. Analytical solution is obtained using Laplace transform technique when dispersivity depended on velocity. The effects of first order decay term and adsorption are studied. The graphical representations are made using

Improved power simulation of AlGaN/GaN HEMT at class-AB operation via an RF drain–source current correction method

A new modified Angelov current–voltage characteristic model equation is proposed to improve the drain–source current（Ids） simulation of an Al Ga N/Ga N-based（gallium nitride） high electron mobility transistor（Al Ga N/Ga N-based HEMT） at high power operation. Since an accurate radio frequency（RF） current simulation is critical for a correct power simulation of the device, in this paper we propose a method of Al Ga N/Ga N high electron mobility transistor（HEMT）nonlinear large-signal model extraction with a supplemental modeling of RF drain–source current as a function of RF input power. The improved results of simulated output power, gain, and power added efficiency（PAE） at class-AB quiescent bias of Vgs =-3.5 V, Vds= 30 V with a frequency of 9.6 GHz are presented.

Realization of a source-device-independent quantum random number generator secured by nonlocal dispersion cancellation

Quantum random number generators(QRNGs)can provide genuine randomness by exploiting the intrinsic probabilistic nature of quantum mechanics,which play important roles in many applications.However,the true randomness acquisition could be subjected to attacks from untrusted devices involved or their deviations from the theoretical modeling in real-life implementation.We propose and experimentally demonstrate a source-device-independent QRNG,which enables one to access true random bits with an untrusted source device.The random bits are generated by measuring the arrival time of either photon of the time–energy entangled photon pairs produced from spontaneous parametric downconversion,where the entanglement is testified through the observation of nonlocal dispersion cancellation.In experiment,we extract a generation rate of 4 Mbps by a modified entropic uncertainty relation,which can be improved to gigabits per second by using advanced single-photon detectors.Our approach provides a promising candidate for QRNGs with no characterization or error-prone source devices in practice.

New blind estimation method of evoked potentials based on minimum dispersion criterion and fractional lower order statistics

Evoked potentials (EPs) have been widely used to quantify neurological system properties. Tra-ditional EP analysis methods are developed under the condition that the background noises in EP are Gaussian distributed. Alpha stable distribution, a generalization of Gaussian, is better for modeling impulsive noises than Gaussian distribution in biomedical signal proc-essing. Conventional blind separation and es-timation method of evoked potentials is based on second order statistics or high order Statis-tics. Conventional blind separation and estima-tion method of evoked potentials is based on second order statistics (SOS). In this paper, we propose a new algorithm based on minimum dispersion criterion and fractional lower order statistics. The simulation experiments show that the proposed new algorithm is more robust than the conventional algorithm.

Dispersion Limit for IM/DD Fiberoptic Transmission Systems

A general formula for the dispersion limit of single-mode-fiber IM/DD (Intensity Modulation /Direct Detection) systems is derived for arbitrary given normalized pulse width P, eye opening penalty X and source linewidth enchancement factor α. From the comparison with published theoretical results, computer simulation and experimental data, its validity and convenience in system design and evaluation are shown. Using this simple and general formula, one can easily obtain the dispersion limit of various fiber types under different working conditions in IM/DD systems.

Static and Dynamic Indicators in the Analysis of Internal Sources of Companies＇ Investments Financing

The Republic of Serbia is characterized by an unsatisfactory macroeconomic environment. Under the conditions of an evident shortage of liquid assets, the financial capital has moved from real to the financial sector, which led companies to over-indebtedness and shutdown of their own capacities. Therefore, capital investments largely depend on internal financing sources and the ability of companies to internally generate funds for investments. In this regard, an emphasis is placed on the difference in the assessment of the company＇s investment capacity based on internal financing sources, which are measured using static and dynamic indicators in order to prove the necessity of applying dynamic coefficients, which are unfortunately not present in our domestic practice. The paper examines and proves the advantages of the use of the dynamic approach for such analyses using the example of energy sector, which is one of the most important branches in Serbian economy.

基于主被动源频散曲线拼接策略的面波频散曲线反演研究

面波勘探是浅地表勘查的主要方法之一,传统的主动源面波方法探测深度通常在30 m以浅,且在噪声干扰复杂的城市环境中作用严重受限;被动源面波正是利用背景噪声为信号源,探测深度大,但对浅层介质分辨能力较差。为此,提出一种主动源、被动源面波数据处理方法,兼顾勘探深度和浅层分辨率。首先对主动源和被动源数据的频散曲线进行拼接,从而获得更宽频带的多阶频散曲线。然后采用数值模拟并反演处理,验证主被动面波频散曲线拼接策略的有效性。通过实测数据处理,对比分析了主动源方法和拼接策略的反演效果,证明了主被动源频散曲线拼接策略能有效提高反演结果精确度。该策略解决了单一震源能量频带有限对反演结果造成的影响,为面波勘探提供了新的手段。

六分量地震观测在工程勘查中的应用试验

利用面波频散曲线反演地下介质的S波速度结构,是浅层工程地震领域一种重要的方法技术.传统的面波法包括主被动源的面波多道分析方法(MASW)和被动源的空间自相关(SPAC)方法,均需要多台地震仪同时记录地面振动;而记录平动和旋转运动的单台站六分量地震数据理论上也可以获得面波频散曲线.本文以河北唐山城区煤矿采空区浅层工程勘探实际六分量地震数据为例,对比了利用单台站六分量地震数据与主、被动源法多台站提取的Rayleigh波频散曲线.试验结果表明利用纵波扫描可控震源时,30 Hz以下频段利用单台站六分量地震数据提取的基阶Rayleigh波频散曲线与主、被动源MASW方法提取的频散曲线结果一致,说明在浅层工程地震勘查中,利用单物理点的六分量地震观测反演浅层横波速度是可行的.

多途混响环境中声扩频信号线性与相关性分析

为分析浅海多途信道中声扩频信号的相关性和线性,建立了计入频率衰减与海底损耗的浅海Pekeris波导虚源法计算模型;对浅海中的脉冲信号与扩频信号进行了仿真计算,通过混响室试验初步研究了多途混响环境中扩频信号的线性。仿真结果显示:虚源法和简正波法的频域解一致,得到了与简正波理论相同的低频模式频散现象,验证了虚源法适用于浅海理想波导、Pekeris波导中的低频问题;当发生模式频散,低频扩频信号的相关性能强于同扩频参数的高频信号。试验结果表明:低频脉冲的时域波形发生畸变、展宽时,同频率的扩频信号能准确测出反射信号的几何时延,证明了低频多途效果仍可看作每个“路径”信号的线性叠加。

CMOS红外光源的设计与实现

基于红外气体传感器微型化、低成本和低功耗的发展需要,设计了一种用于非色散红外(NDIR)集成气体传感器的互补金属氧化物半导体(CMOS)红外光源。它以非等间隔的蛇形钨(W)薄膜电阻作为加热丝,以二氧化硅(SiO_(2))和氮化硅(Si_(3)N_(4))多层复合介质薄膜为支撑形成悬空膜片式微热板,以氧化铜(CuO)和二氧化锰(MnO_(2))纳米材料复合薄膜作为辐射增强层。基于COMSOL软件进行了热电耦合仿真,证明结构设计合理性。采用标准CMOS工艺、硅(Si)的深刻蚀工艺以及静电流体动力学打印技术流片制造了该CMOS红外光源芯片。性能测试结果表明:该红外光源从室温升温至469℃的热响应时间约为41 ms,电功耗仅为138 mW,辐射区温度分布均匀,引入辐射增强层使表面比辐射率提高约35%,红外光源的辐射功率和红外光谱辐射强度测试结果表明:该涂层有效地增强了红外辐射。

超短时长被动源面波成像在浅地表空洞识别中的应用

为解决城市物探工作中由于勘探场地的监管限制导致无法进行长时间数据采集工作的问题,笔者使用超短时长被动源噪声数据,通过相位加权叠加互相关函数法提取出频散曲线,并对基阶频散曲线反演得到一维横波速度剖面,以一维横波速度剖面为初始模型反演得到第二阶段反演结果,指示出地下空洞的存在。研究结果表明超短时长被动源面波成像方法在空洞识别方向应用的可行性。

闭式注水油藏自分散型耐高温高盐调驱剂

南海东部高温高盐油藏闭式注水井无地面注水流程,常规调驱剂无法在地面混配后注入地层,且由于自分散性差,难以直接注入地层。以南海东部A油田为目标,从快速自分散和耐高温高盐两个角度出发,以2-丙烯酰胺-2-甲基丙磺酸(AMPS)含量为40%的耐温耐盐聚合物为基础,辅以多酚类复合交联剂、多支链醇聚醚类分散剂等,通过反应成胶、机械研磨,制得自分散型耐高温高盐调驱剂。采用激光粒度仪、电子显微镜、动态光散射仪等,对调驱剂的粒径、微观形貌和表面电性进行了表征,评价了调驱剂的自分散性能、注入性能和剖面调整性能,并在南海东部A油田X井组进行了现场应用。结果表明,自分散型耐高温高盐调驱剂呈球形,初始粒径D50(粒径中值)为1.09~11.63μm,通过调整配方、研磨条件或加热时间可调节调驱剂的粒径。调驱剂颗粒表面呈负电,Zeta电位值为-19.30~-26.1 mV。与常规油分散型颗粒调驱剂相比,该调驱剂自分散性好,遇水后能快速均匀分散,在注入水中的自分散率为90.0%,岩心注入压力仅为油分散型颗粒调驱剂的53.13%。调驱后,高渗透岩心的分流量由92.6%降至20.5%,低渗透岩心的分流量由7.4%增至79.5%,吸水剖面明显“反转”。现场实施效果良好,调驱剂施工爬坡压力为0.5 MPa,施工后最高日增油106 m3,阶段增油8900 m3。该调驱剂满足目标油田高温高盐条件,注入性好,增油效果明显,适合闭式注水油藏调驱。

潍坊地区地层频散特征与分析研究

潍坊市南部山区第四系厚度较薄,北部地区为冲洪积平原,第四系厚度较大,由南向北逐渐增厚,且潍坊市北部为滨海咸水入侵区,传统的物探方法,尤其是电法、电磁法,在该区开展工作效果欠佳。本次研究借鉴地震勘探多次覆盖观测系统的思路,利用线形台阵多次覆盖的高效微动探测技术,对潍坊市不同地层的面波频散特征进行分析研究,并根据频散特征差异对地层结构进行了划分。研究结果表明:潍坊市南部浅覆盖区频散曲线频点范围较广,整体呈表层低速中深层迅速升高型;潍坊市北部厚覆盖区频散曲线频点范围相对较窄,整体呈表中深缓慢升高低速型;古河道发育地层频散曲线出现无规律的跳动或“之”字形拐点,整体为深层波速最高中部低速型。

城市硬质路面对噪声源面波数据的影响特征与优化处理方法

被动源面波勘探方法对城市复杂环境具有较好的适应性,在城市浅层地震高分辨勘探的要求下,城市硬化路面对面波勘探的影响不容忽视。因此基于广州市临江城区道路开展现场试验,主要针对城市硬化路面对被动源面波数据采集及处理的影响作用进行了分析,发现城市硬化路面中存在速度高于面波的高速直达波,严重影响了面波频散曲线的提取。提出了基于频率-波数域滤波(Frequency-Wavenumber Filtering,F-K Filtering)的高速直达波压制方法,有效恢复了地下介质面波的频散成分。该方法的成功应用,为城市硬化路面面波勘探提供了一种有效的数据处理方法。

综采工作面多尘源下呼吸带粉尘分布特征研究

综采工作面呼吸带粉尘污染是威胁矿工生命健康的直接因素,为了降低粉尘对作业人员的危害,建立新桥煤矿某综采工作面的三维实体模型,利用Fluent数值模拟多尘源工况下粉尘在巷道中扩散轨迹,研究呼吸带区域粉尘的分布特征,并结合现场实测数据对主要产尘点及沿程呼吸带高度的粉尘分散度进行分析。实验结果表明,顺风割煤时,采煤区下风侧20 m为粉尘主要沉降区,60 m内为粉尘高污染区域;呼吸带中以小于30μm的粉尘颗粒为主,回风巷呼吸带高度10μm以下可吸入粉尘颗粒占比在54%以上,远高于采煤工作面;转载点产尘是导致回风巷呼吸带中10μm以下粉尘比例增加的重要因素。以此为理论基础,有针对性地制定呼吸带粉尘防治措施,对煤矿安全生产以及作业人员健康具有重要意义。

浅地表环境下ESPAC微动成像方法影响因素分析

扩展空间自相关(ESPAC)微动探测(天然源面波勘探)技术由于其简便快捷、效果精确等优势,在浅部地层探测方面得到广泛应用。然而在实际应用中会出现基于ESPAC法提取的频散能量成像效果不尽人意的现象,特别是不同的观测台阵布置情况会对采集的频散曲线提取结果造成一定的影响。通过对ESPAC法成像原理的分析研究,利用背景噪声模拟的方法进行了天然源微动记录模拟实验,比较了不同子波主频分布情况下频散能量的差异,定量分析了不同台站布置情况和采集时间长度对频散能量成像质量的影响,经过对比研究得到了ESPAC法在浅地表勘探时的成像规律,在兼顾效率和探测成本的条件下最大程度提高基阶模式下的频散能量成像质量。将研究结果应用到工程实例中,取得了不错的实际勘探效果,验证了模拟结果的实用性。