Estimation of Aquifer Transmissivity Using Dar Zarrouk Parameters at Ogbozara-Ekwegbe-Agu and the Environ, Enugu State, Nigeria

This study was undertaken to determine the hydrologic properties of the aquifer materials at Ogbozara-Opi/Ekwegbe-Agu and environs by the estimation of the aquifer transmissivity using Dar Zarrouk parameters. The study area lies in the Anambra basin and is underlain, from bottom to top, by 3 prominent geologic formations;Enugu Formation, Mamu Formation and Ajali Formation respectively. A total of 19 sounding stations were occupied within the study area using the Ohmega resistivity meter. The VES data were interpreted using the conventional partial curve matching technique to obtain initial model parameters which were later used as input data for computer iterative modelling using the Interpex software. These analyses were further combined with information from two existing boreholes in the study area to estimate aquifer hydraulic parameters using Dar-Zarrouk parameters. The layer parameters thus obtained revealed that the dominant curve type obtained from the different formations is the AK curve type followed by the HK curve type. An average of 6 geo-electric layers were delineated across all transect taken with resistivity values ranging from 25.42 - 105.85 Ωm, 186.38 - 3383.3 Ωm and 2992.3 - 6286.4 Ωm in the Enugu, Mamu and Ajali Formations respectively. Results of the study revealed the aquifer resistivity in the study area ranges from 1 - 500 Ωm. The depth to the water table range from 13 - 208 m with a mean value of 76.05, while aquifer thickness varies between 95 and 140 m with a mean value of 102.89 m. The values of the Dar-Zarrouk parameters revealed that the transverse resistance varies between −10,000 - 170,000 Ωm2, while the longitudinal conductance varies from 0.1 - 1 to 1.9 Ω - 1. Similarly, the hydraulic conductivity in the area ranges from 5 to 50 m/day, while the transmissivity values range from 1000 to 14,000 m2/day.

Aquifer Test求群孔抽水试验水文地质参数

在水文地质条件复杂的地区,往往采用大型的群孔抽水试验充分揭露含水层特征,获取水文地质参数。用Aquifer Test软件求解水文地质参数,则方便实用、简捷高效,可快速输出拟合图形和求参结果。Aquifer Test提供了丰富的求参方案,求参必须结合当地当时的水文地质条件实际情况考虑,选择适合的方案和时空数据求取水文地质参数。

Evaluation of aquifer hydraulic properties from resistivity and pumping test data in parts of Gwagwalada,Northcentral Nigeria

Population upsurge in Gwagwalada increased water demand in the area,thereby stressing water resources in the area.Aquifer properties in parts of Gwagwalada in North-Central Nigeria were therefore investigated using resistivity and hydrogeological approaches.Static water level measurements of hand dug wells were used to determine the groundwater flow direction for the area which coincides with the North East-South West joint direction.Constant rate pumping test was adopted for the research and 10 boreholes were pumped.The weathered/fractured basement range from 7.5 m to 56.7 m.The transmissivity values in the area ranged from 0.35 m^(2)/d to 3.63 m^(2)/d while the hydraulic conductivity range from 0.045 m/d to 0.18 m/d.The Vertical Electrical Soundings(VES)were carried out on the area.The geoelectric sections revealed four to five layers and the longitudinal conductance varied from 0.11Ω^(-1)to 0.37Ω^(-1).The results of the investigation characterized the groundwater potential in the study area into low and moderate while the aquifer protective capacity into weak and moderate zones.The efficacy of resistivity and pumping test data in quantifying aquifer properties has been established in this study.The findings of this study shed light on the properties of ground water and aquifer protective capacity in the area,hence assist in the effective future groundwater resources exploitation.

Variation characteristics of aquifer parameters induced by groundwater source heat pump operation under variable flow

The variation characteristics of aquifer parameters,induced by groundwater source heat pump(GWSHP) operation under variable flow,were theoretically analyzed through a case study,in which the characteristics of building air conditioning load were considered.The results,compared with the constant flow operation,indicate that the influence on the variations of porosity,hydraulic conductivity and confined water head is decreased by 48%,51% and 71%,respectively,under variable flow operation.The security of variable flow operation is superior to that of constant flow.It is also concluded that the climate region and function of the buildings are primary factors which affect the suitability of variable flow operation in GWSHP.

Using Grey Relational Analysis to Evaluate Different Influencing Factors on Aquifer Parameters Variations with Groundwater Source Heat Pump Operation

The influence of particle migration induced by groundwater source heat pump( GWSHP) operation on aquifer parameters was theoretically analyzed. Then the sensitivity analysis of different influencing factors,which influenced aquifer parameters with GWSHP operation,was evaluated by using grey relational analysis method through a case study. The present study indicated that the erosion parameter, hydraulic conductivity and initial concentration were critical influencing factors which affected the aquifer parameters and the suitability of GWSHP. It also indicated that the discharge of single well should be controlled and the diameter of single well should be selected appropriately in order to decrease particle migration.

Genetic algorithms and aquifer parameter identification

In order to identify aquifer parameter,authors develops an improved combinatorial method called best chromosome clone plus younger generation chromosome prepotency genetic algorithm (BCC-YGCP-GA), based on a decimal system simple genetic algorithm (SGA). The paper takes unsteady state flows in a two dimensional, inhomogeneous, confined aquifer for a ideal model, and utilizes SGA and BCC-YGCP-GA coupled to finite element method for identifying aquifer hydraulic conductivity K 1 ,K 2 ,K 3 and storage S 1 ,S 2 ,S 3 , respectively. It is shown from the result that GSA does not reach convergence with 100 generations, whereas convergence rate of BCC-YGCD-GA is very fast. Objective function value calculated by BCC-YGCD-GA is 0 001 29 with 100 generations, and hydraulic conductivity and storage of three zones are almost equal to the "true" values of ideal model.

Aquifer parameter identification by the best chromosome clone plus younger generation chromosome prepotency genetic algorithm

This paper developed an improved combinatorial method called the best chromosome clone plus younger generation chromosome prepotency genetic algorithm （BCC-YGCP-GA） to evaluate aquifer parameters. This method is based on a decimal simple genetic algorithm （SGA）. A synthetic example for unsteady-state flow in a two-dimensional, inhomogeneous, confined aquifer containing three hydraulically distinct zones, is used to develop data to test the model. The simulation utilizes SGA and BCC-YGCP-GA coupled to the finite element method to identify the mean zonal hydraulic conductivities, and storage coefficients of the three-compartment model. For this geometrically simple model, used as a prototype of more complex systems, the SGA does not reach convergence within 100 generations. Conversely, the convergence rate of the BCC-YGCD-GA model is very fast. The objective function value calculated by BCC-YGCD-GA is reduced to 1/1 O00th of the starting value within 100 generations, and the hydraulic conductivity and storage of three zones are within a few percent of the “true” values of the ideal model, highlighting the power of the method for aquifer parameterization.

Assessment of the Protective Capacity of Vadoze Zone over Aquifer Systems Using Secondary Geoelectrical Parameters: A Case Study of Kaltungo Area North East, Nigeria

An assessment of the protective capacity of the vadose zone overlyingthe aquifer systems in the Kaltungo area was carried out to determine itsinfluence on groundwater quality. Applying the schlumberger array with amaximum electrode spread AB/2 = 100m through VES, thirty water wellpoints were surveyed using Omega terrameter (PIOSO1) resistivity meter.The field data was first subjected to manual interpretation through curvemarching and then digitized modeled curves using computer software. Theinterpreted data revealed that the area is characterized by eleven differentcurve types representing three to five geo electrical layers. In order toassess the protective capacity of the vadoze zone over the aquifer systems,the longitudinal conductance (S) and transverse resistance (T) (secondarygeoelectric parameters) were computed from the primary data using theDar Zarouk formula. The values of S obtained range from 0.0018 to 0.4056ohms with a mean value of 0.0135 ohms while the values of T range from0.55 ohms to 1195.68 ohms with a mean value of 39.84 ohms. The valuesof S and T obtained reveal that 90% of probed points has poor protectivecapacity, 10 % has moderate protective capacity and 83 % has hightransmissivity, 17 % has intermediate transmissivity. The T and S values areskewed towards poorly protective capacity thus making groundwater in thearea highly vulnerable to contamination from the surface. To achieve goodgroundwater quality in the area, proper completion of newly constructedwells should install protective casing through the entire vadose zone.

Characterization of Subsurface Lithology and Aquifer Parameters Using Vertical Electrical Sounding(VES)for Groundwater Development in Igbo-Imabana,Southern Nigeria

Vertical Electrical Soundings(VES)using Schlumberger array was carried out at fifteen(15)different points to evaluate aquifer characteristics within Igbo-Imabana,Abi L.G.A of Cross River State.Resistivity meter and its accessories were used for data acquisition.The maximum current and potential electrode distance were 400 m and 20 m respectively.The field data were interpreted using Interpex software and three to five geo-electric layers encountered within the study area.The dominant curve type was H followed by K.From the result,geo-electric layers delineated were sandstone,clay,saturated sandstone,sandy shale,clayey shale,and shale with average apparent resistivity values of 2249.94Ωm,2.86Ωm,365.28Ωm,222.69Ωm,14.60Ωm and 59.02Ωm respectively.The top geoelectric layer was dominantly lateritic topsoil,with variation in degrees of compaction and having an average resistivity of 876.33Ωm with depth and thickness generally less than 5 m.The calculated aquifer parameters hydraulic conductivity(K_(c)),transmissivity,longitudinal conductance,and transverse resistance from the VES results show ranges values;3.86×10^(-4)to 4.69×10^(-2)m/day,2.95×10^(-3)to 2.82 m^(2)/day,2.95×10^(-3)to 2.81Ωm and 484.33 to 19444.83Ω^(2)m respectively.The aquifer thickness and depth values range from 3.60 m to 68.05 m and 5.20 m to 76 m respectively.The study reviewed that the area is made of heterolithic/heterogenous lithofacies,confined aquifer(s),shallow and deep aquifer.Also,from the models and aquifer parameters,the area is characterized by semipervious materials.This integrally explains why the area have have low transmissivity and majority of boreholes drilled in the area failed.

Aquifer Test计算越流承压含水层水文地质参数方法研究

为了准确评价越流承压含水层地下水资源量,探寻一种简便精确计算水文地质参数方法成为关键性问题。利用清丰县八里庄水源地勘探项目非稳定流越流承压含水层抽水试验资料,采用Aquifer Test软件,根据越流承压含水层非稳定井流理论,计算承压含水层的水文地质参数,并对其计算结果与采用数值模拟方法所得结果进行比较分析。结果表明:Aquifer Test软件对水文地质参数的计算简便快捷,计算结果符合水文地质实际情况,是合理选择越流承压含水层水文地质参数较为精确的方法。

Decisive Role of Gravitational Parameter G in Cosmology

In 1937, P. Dirac proposed the Large Number Hypothesis and the Hypothesis of the variable gravitational “constant”, and later added the notion of continuous creation of Matter in the World. The Hypersphere World-Universe Model (WUM) follows these ideas, albeit introducing a different mechanism of Matter creation. In this paper, we show that Gravitational parameter G that can be measured directly makes measurable all Cosmological parameters, which cannot be measured directly.

在片S参数计量比对结果浅析

中国电子科技集团公司第十三研究所作为主导实验室开展了在片S参数计量比对工作,对参比实验室提交的在片S参数测量结果进行了汇总分析,并用E_n值对各参比实验室测量结果进行了评价。通过在片S参数计量比对,确保了量值传递的准确、可靠,特别是对在片S参数测量不确定度的主要来源统一了认识。同时也为业内提供了在片S参数测量一致性的比较平台。

高速S-CO_(2)向心透平几何参数优化及变工况特性分析

透平是热力循环中实现热功转换的核心设备,优化透平几何参数以改善气动性能,是提升系统热效率的关键。该文以面向某船舶主机烟气余热利用的超临界二氧化碳布雷顿循环透平设计参数为基础,给出向心透平主要几何参数,采用耦合CO_(2)真实物性参数的CFX仿真方法,分析几何参数动、静叶包角以及叶轮出口几何角对透平性能的影响规律并进行参数优化,进一步研究非设计工况下的透平运行特性。结果表明:增大静叶包角会使动叶前缘出现扰动涡流并减少余速损失,增大叶轮出口几何角,动叶包角对透平效率的影响规律不变,但效率峰值点会沿动叶包角减小的方向移动;动、静叶包角和叶轮出口几何角分别为49°、21.5°、25°时透平设计点总-静等熵效率高达87.99%,相比优化前,提高0.54个百分点;透平偏离设计点±20%工况下等熵效率大于80%。结果可为超临界二氧化碳高速向心透平设计提供一定参考。

基于Aquifer Test的底板放水试验参数计算与评价研究

为了提高放水试验参数计算的精度和速度,基于地面抽水试验和井下底板放水试验在水文地质参数计算中的相似性,将抽水试验中常用的Aquifer Test求参软件用于宁东灵新煤矿底板承压含水层放水试验的参数求解中,分别采用了标准曲线对比法、直线图解法和水位恢复法对渗透系数K和贮水系数μ*进行了拟合求解,并和手工方式下的计算过程及结果进行了对比和分析。结果显示,采用手工和软件计算所得参数的平均值总体上无较大差异,但手工方式在不同方法下的拟合结果存在较大的离散性和不确定性,而Aquifer Test软件由于融合了人工拟合和机器拟合两者的优势,所得结果精度显著高于前者,同时较前者具有操作过程简易、计算结果同步等优点,适合在有多个观测孔的底板放水试验参数计算中推广应用。

A Hydrogeophysical Model of the Relationship between Geoelectric and Hydraulic Parameters, Central Jordan

Geoelectrical soundings using the Schlumberger array were carried out in the vicinity of 23 pumping test sites to determine aquifer parameters, central Jordan. On the basis of aquifer geometry, the area has been di-vided into two hydraulic units: the northern flood plain and the flood plain to its south. Field resistivity data are interpreted in terms of the true resistivity and thickness of subsurface layers. These parameters are then correlated with the available pumping test data. Significant correlations between the transmissivity and modified transverse resistance as well as between the hydraulic conductivity and formation factor were ob-tained for the two hydraulic units, in central Jordan are presented here.

Dynamics and adaptive control of a dual-arm space robot with closed-loop constraints and uncertain inertial parameters

A dynamics-based adaptive control approach is proposed for a planar dual-arm space robot in the presence of closed-loop constraints and uncertain inertial parameters of the payload. The controller is capable of controlling the po- sition and attitude of both the satellite base and the payload grasped by the manipulator end effectors. The equations of motion in reduced-order form for the constrained system are derived by incorporating the constraint equations in terms of accelerations into Kane＇s equations of the unconstrained system. Model analysis shows that the resulting equations perfectly meet the requirement of adaptive controller design. Consequently, by using an indirect approach, an adaptive control scheme is proposed to accomplish position/attitude trajectory tracking control with the uncertain parameters be- ing estimated on-line. The actuator redundancy due to the closed-loop constraints is utilized to minimize a weighted norm of the joint torques. Global asymptotic stability is proven by using Lyapunov＇s method, and simulation results are also presented to demonstrate the effectiveness of the proposed approach.

Soil Parameter Identification for Wheel-terrain Interaction Dynamics and Traversability Prediction

This paper presents a novel technique for identifying soil parameters for a wheeled vehicle traversing unknown terrain. The identified soil parameters are required for predicting vehicle drawbar pull and wheel drive torque, which in turn can be used for traversability prediction, traction control, and performance optimization of a wheeled vehicle on unknown terrain. The proposed technique is based on the Newton Raphson method. An approximated form of a wheel-soil interaction model based on Composite Simpson＇s Rule is employed for this purpose. The key soil parameters to be identified are internal friction angle, shear deformation modulus, and lumped pressure-sinkage coefficient. The fourth parameter, cohesion, is not too relevant to vehicle drawbar pull, and is assigned an average value during the identification process. Identified parameters are compared with known values, and shown to be in agreement. The identification method is relatively fast and robust. The identified soil parameters can effectively be used to predict drawbar pull and wheel drive torque with good accuracy. The use of identified soil parameters to design a traversability criterion for wheeled vehicles traversing unknown terrain is presented.

Uncertainty and Sensitivity Analyses of the Simulated Seawater—Freshwater Mixing Zones in Steady-State Coastal Aquifers

The uncertainty and sensitivity of predicted positions and thicknesses of seawater-freshwater mixing zones with respect to uncertainties of saturated hydraulic conductivity, porosity, molecular diffusivity, longitudinal and transverse dispersivities were investigated in both head-control and flux-control inland boundary systems. It shows that uncertainties and sensitivities of predicted results vary in different boundary systems. With the same designed matrix of uncertain factors in simulation experiments, the variance of predicted positions and thickness in the flux-control system is much larger than that predicted in the head-control system. In a head-control system, the most sensitive factors for the predicted position of the mixing zone are inland freshwater head and transverse dispersivity. However, the predicted position of the mixing zone is more sensitive to saturated hydraulic conductivity in a flux-control system. In a head-control system, the most sensitive factors for the predicted thickness of the mixing zone include transverse dispersivity, molecular diffusivity, porosity, and longitudinal dispersivity, but the predicted thickness is more sensitive to the saturated hydraulic conductivity in a flux-control system. These findings improve our understandings for the development of seawater-freshwater mixing zone during seawater intrusion processes, and give technical support for groundwater resource management in coastal aquifers.

Investigation of ductile iron casting process parameters using Taguchi approach and response surface methodology

To find the optimized levels of various casting parameters in the ductile iron casting, various casting defects and the rejection rate were observed from a medium scale foundry. The controlled values of different casting parameters such as pouring temperature, inoculation, carbon equivalent, moisture content, green compression strength, permeability and mould hardness were selected. Three different melts of metal with 0.4wt.%, 0.6wt.%, and 0.8wt.% inoculation （Fe-Si-Mg alloy and post inoculant） were produced using a 1-ton capacity coreless medium frequency induction furnace. L-27 orthogonal array with 3-level settings were chosen for the analysis. Responses for each run were observed. The signal-to-noise （S/N） ratio for each run was calculated using the Taguchi approach, and the optimized levels of different casting parameters were identified based on the SIN ratio. The analysis of variance for the casting acceptance percentage concludes that inoculation is the most significant factor affecting the castings＇ quality with a contribution percentage of 44%; an increase in inoculation results in a significant improvement in acceptance percentage of ductile iron castings. The experiment results showed that with the optimized parameters, the rejection rate was reduced from 16.98% to 6.07%.

S Phase Cell Percentage Normalized BrdU Incorporation Rate, a New Parameter for Determining S Arrest

In this study, a new parameter, S phase cell percentage （S fraction） normalized BrdU （SFN-BrdU） incorporation rate, was introduced to detect $ arrest. The results showed a positive linear correlation between the BrdU incorporation rate and the S fraction in unperturbed 16HBE cells. Theoretical analysis indicated that only S arrest could result in a decrease in the SFN-BrdU incorporation rate. Additionally, the decrease in SFN-BrdU incorporation rate and the activation of DNA damage checkpoints further demonstrated that S arrest was induced by diethyl sulfate treatment of 16HBE cells. In conclusion, $FN-BrdU incorporation rate can be used to detecting S arrest.