Maximum Spacing Research Articles

Integrated hydrogeophysical and GIS based demarcation of groundwater potential and vulnerability zones in a hard rock and sedimentary terrain of Southern India

This research has identified the groundwater potential and vulnerability zones in Tiruchirappalli district of Tamil Nadu, India. The Schlumberger electrode array has been used to conduct vertical electrical sounding (VES) at 95 sites with a maximum electrode spacing of 150 m. The study area comprises of hard rock and sedimentary formations. Geographical Information System (GIS) has been used to integrate the geoelectrical data and to prepare spatial variation maps for various parameters. Finally, groundwater potential and vulnerability zones have been demarcated, and these outputs have been validated using water level and nitrate data, respectively. The Dar-Zarrouk parameters such as longitudinal conductance (S), transverse unit resistance (T), and aquifer anisotropy (λ) have been used along with the spatial variation of resistivity and aquifer thickness to find out groundwater potential areas with the support of GIS. The thickness of topsoil, weathered zone and fractured zone are not uniform in the research area. Top soil plus weathered zone acts as a water table (phreatic) aquifer, which extends up to 38 m from the surface. Fractured zone extends up to 45 m, which acts as a kind of confined/semi-confined aquifer. Open and bore wells have been constructed to tap groundwater from the unconfined (water table) and confined/semi-confined aquifers, respectively. High to very high groundwater potential areas are associated with low resistivity, high thickness, low longitudinal conductance, high transverse unit resistance and high aquifer anisotropy areas. Very high groundwater potential areas are mostly confined to flood plain (alluvium) deposits in the central portion of the study area. High potential areas are noticed in the northern part, whereas low potential areas are noticed in the southern part. The areas with high longitudinal conductance indicate low permeable zones with less possibility of external pollution. Since agriculture is an important activity in the study region, this work will be useful to provide water supply for irrigation as well as for domestic needs.

Car and train platoon simulations

Detailed simulations of car and train platoons are critical steps towards successful implementations of the platooning technologies. This paper developed a simulation method that can be used for both car and train platoon simulations. The method includes three main parts: (1) a scalable adaptive longitudinal space controller, (2) 2D multibody dynamics simulations that consider wheel-rail contact (Polach model), tyre-road contact (Magic Formula), suspensions and in-train forces, and (3) a scalable parallel computing method that processes the dynamics simulation of each individual vehicle (one car or one carriage) by using one independent computer core. Two case studies were conducted to simulate a 6-car platoon and a 3-train platoon on real-world road and track. The maximum space errors for the car platoon and the train platoon results were about 0.32 and 0.23 m, respectively. When the platoons were running at a steady speed, space errors were well controlled within ±0.05 m for both car and train platoons. Example dynamics results were presented including wheel-rail contact forces, tyre-road contact forces, and carbody vibrations. This information can be used to conduct a wide range of related studies such as passenger ride comfort and system damage assessments.

Flexural behavior of reinforced concrete beams strengthened with high-strength stainless steel wire rope meshes reinforced ECC

In this study, the flexural behavior of reinforced concrete (RC) beams strengthened with high-strength stainless steel wire rope (HSSSWR) meshes reinforced Engineered Cementitious Composite (ECC) was investigated. In total, six strengthened beams and one control beam were manufactured and tested taking into account of test variables including the reinforcement ratio of longitudinal HSSSWR, nominal diameter of HSSSWR, and formula of ECC. The test results showed that the flexural capacity, ductility, stiffness, and toughness of the strengthened beams were sufficiently improved, and the development of crack including maximum width and spacing was delayed by using the strengthening system of HSSSWR meshes reinforced ECC, and the failure mode of the strengthened beams was concrete crushing, which was followed by the local debonding along the interface and rupture of reinforcement layer except for the beam with the relatively high reinforcement ratio of longitudinal HSSSWRs. The calculation models with high accuracy were proposed to predict the flexural capacity and stiffness for the RC beams strengthened by the HSSSWR meshes reinforced ECC, which were verified by test results in this study and existing study.

Molecular Dynamics Simulation for Separation Performance of PDMS/Fluorosilane Membrane with Different Mass Ratios in Acetone–Water Mixture

AbstractPolydimethylsiloxane (PDMS) membrane in suitable‐fluorinated level have excellent pervaporation performance as well as antibiological contamination performance. The pervaporation membranes with different PDMS/fluorosilane mass ratios, the adsorption and dissolution behaviors of acetone molecules on the membrane surface, as well as the diffusion and permeation behaviors in the membranes are studied by all‐atom molecular dynamics simulation (AAMDS). The results show that when the mass ratio of PDMS/fluorosilane is 100/20, the surface solubility of acetone is 11.711 (J cm−3)0.5, and the interfacial interaction is −16897.0415 kcal mol−1, both of which are the highest. The results of wide‐angle X‐ray diffraction (WAXD) showed that there are amorphous regions in the membranes suitable for acetone penetration. The maximum chain spacing of the PDMS/fluorosilane(100/20)_membranes is 10.8482 Å, and the free volume fraction (FFV) is 3.03%, both of which are the largest. The change rate of long‐term mean square displacement (MSD) in PDMS/fluorosilane(100/20)_Membrane with time is 0.45269. The Young's modulus E, shear modulus G, volume modulus K, and Poisson's ratio ν of PDMS/fluorosilane(100/20)_Membrane are 0.3249, 0.4061, 0.0492 GPa and ‐0.5999, respectively. The elasticity of the membrane enhances the diffusion behavior of acetone molecules, and the self‐diffusion coefficient of acetone in the membrane is 0.07545 Å2 ps−1.

Mechanical and thermal stability of Bulk Metallic Glass alloys identified as candidates for space mechanism applications

Extraterrestrial environments expose engineering components to severe operating conditions for extended durations. Challenges of extreme temperature changes and high vacuum are being met by careful selection of available materials or by development of novel high-performance materials and processes. Bulk Metallic Glasses (BMGs) are amorphous alloys that exhibit very high strengths, hardness, strain energy storage, corrosion resistance, and the capacity for thermoplastic formability, and are of interest in space engineering design. Using criteria driven by the requirements of specific space-based mechanisms, BMG alloys were selected from the literature for processing and performance evaluation. Alloys particularly suited for gearing applications and flexure-based compliant mechanisms were identified and standard test specimens produced. Four Zr-based BMG alloys were selected for analysis: Zr53Al16Co23.25Ag7.75, Cu47Zr46Al5Y2, Zr49Ti1.96Cu37.24Al9.8Y2, and Zr60Ti2Nb2Al7.5Ni10Cu18.5, with compositions in at.%. Presented in this work are the results of compression testing, fatigue testing, and differential scanning calorimetry; previous results of wear and hardness testing have been presented elsewhere. A maximum space service temperature of 400 °C is considered. The alloys exhibited significant differences in processability and thermomechanical performance. The alloy Zr49Ti1.96Cu37.24Al9.8Y2 exhibited the best overall performance for gearing applications; and Zr60Ti2Nb2Al7.5Ni10Cu18.5 was the best alloy for compliant flexures.

Impact of Slope Orientation on Inlet Spacing: Gutter Flow Analyses

A roadway’s capacity to drain itself is of utmost importance for the safety and comfort of its users. Standing water and any amount of channelized flow on roadways create nuisances to the users, and the extent of encroachment into the lanes and the water-film thickness over the lanes are crucial for motorists with relatively high speed. Guidelines cover a wide range of subjects from size and type of inlets, which capture the channelized flow for conveyance into enclosed drains, to the decision for slope orientation, but the guidelines seem to lack in checking the depth of channelized flow. HEC-22 (the urban drainage design manual of US Department of Transportation) endorses limiting the flow depths to curb height (as if the concern is no longer the roadway users) and fixes the criterion for the inlet spacing (restricted to 90 to 150 m) to maximum allowable flow spreads. This study analyzed the maximum allowable inlet spacing via setting three criteria: fixed maximums to flow depth, spread for the channel flow, and to over-lane water-film thickness. The impact of slope orientation on inlet spacing is tested along with some other factors for roadways of two types (local and highway). The results were graphed for various uniform slope orientations under a wide range of rainfall intensities for the determined inlet spacing values. This was performed by combining a kinematic wave equation solution to dismiss the conditions that lead to hydroplaning depths when using the Rational Method and Manning’s equation to obtain water depths and inlet spacings for an inlet of full capture capacity. It is found that the allowable spacing values do not constitute any major restrictions in highway setting (3 m shoulder) in terms of recommended spacing. In the local setting, however, with a maximum spread of 1.8 m, maximum allowable inlet spacing becomes a limitation in many orientations, and slope optimization under such conditions becomes crucial at times when providing the same spacing for two orientations.

Wide Wavelength Selectable and High Frequency Precision of All-Optical Wavelength Conversion Using Pump Light Generated from Optical Combs and SSB Modulation

All-optical wavelength conversion based on four-wave mixing (FWM) in highly nonlinear fiber (HNLF) with wide wavelength selectivity and highly precise frequency controllability was investigated in combination with pump light generated from optical combs and single-side-band (SSB) modulation. Using multiple carriers, optical combs generated using LiNbO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> phase modulators and an SSB phase modulator, pump lights were precisely controlled with a frequency range of 580 GHz and frequency shift of 1.25 GHz. The frequency difference of the pump lights from the ideal one was less than the resolution of an optical spectrum analyzer FWM was performed for single-polarized 10 Gbaud NRZ-QPSK signals in combination with the generated pump lights, and clear eye-openings and constellations for idler signals were achieved. Moreover, a bit error rate (BER) of <3.8 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−3</sup> for all idler lights was achieved. Conversely, in the case of the 1.25 GHz controlled pump light, the constellation was distorted, and the BER was saturated at 2.0 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−4</sup> . In addition, the limit of wavelength convertible bandwidth was investigated to determine the condition for selecting the frequency of wavelength conversion applicable to wavelength defragmentation in the metro/core networks. From the experimental and analytical results, the maximum frequency spacing between the signal and pump was found to be 1403.125 GHz, limited by the wavelength conversion efficiency of the HNLF, whereas the minimum frequency spacing was found to be 25 GHz, restricted by the crosstalk between the signal and pump light that could not be eliminated using the bandpass filter.

Relatively optimal policies for stock management in a supply chain with option for inventory space limitation

Coordination between a single manufacturer (vendor) and a buyer (retailer), via the delivery schedule in joint economic lot–sizing problem for a two stage supply chain, is investigated. To satisfy the buyer’s demands, the product is delivered in discrete equal size sub-batches from the vendor’s stock to the buyer’s stock. Under stock management (SM) policy, the vendor delivers each sub-batch as soon as the buyer’s inventory reduces to zero. For consignment stock (CS) policy, in the case of buyer’s warehouse space limitation, the maximum level of the buyer’s, consequently of the vendor’s, inventory position can be controlled by the vendor’s just in time or delayed deliveries (CS-k policies). If a space limitation is attached to vendor’s warehouse, then the maximum level of the vendor’s, consequently of the buyer’s, inventory position can be controlled by just in time, or advanced for the buyer deliveries (in our notation SM-v-policies). Relatively optimal SM-v-policies can be obtained as solutions of adequate constrained problems. A comparative study, done in this paper, shows that the SM-v-policies can perform better than policies obtained as solutions of the sharply constrained problem where the maximal vendor’s inventory level is equal to the maximum attainable space limit. Numerical examples are presented with appropriate comments to the solutions obtained by the proposed algorithm

Component calibration and configuration planning in assembly automation with a parallel manipulator

Parallel manipulator (PM) is widely used as posture alignment mechanism in heavy component machining and assembly process. To achieve precise kinematics backward transformation, the relative spatial relationship between the component and PM’s spherical joints need be calibrated, which suffers from the pain-point that the spherical joint center is inside the mechanical socket and its position can hardly be directly recovered. We refer this problem as component calibration. In this research, we present an alternate solution by formulating kinematic chain in form of AX = XB based on designedly established PM reference configuration and base coordinate system, which does not rely on the measurement of spherical joint center position. To improve the calibration accuracy, accuracy-influencing factors, PM’s dexterity distribution over workspace and properties of angle-axis space are jointly analyzed then 4 centrosymmetric angle-axis vector pairs on the boundary of maximum feasible angle-axis space at zero manipulator translation are set as configuration pairs to establish the kinematic chain. Configuration planning in angle-axis space facilitates the visualization and control of the critical factors in calibration process and tends to set these factors to optimum simultaneously. Experiments are carried out finally and the results show that the calibration accuracy could be notably improved with such method compared with no configuration planning, especially for translation accuracy. • A component calibration method in assembly automation with parallel manipulator. • Dexterity analysis and calibration configuration planning in angle-axis space. • A fast calibration implementation using fiducial tag and monocular vision.

Application of Vertical Electrical Sounding for the Investigation of Groundwater potentials at Umaru Musa Yar'adua University, Katsina

The population of Umaru Musa Yar’adua University, Katsina (the study area) is increasing every session and therefore, sources of safe water in the area is need to be improved; more importantly groundwater. Recently, water supply from Zobe Dam is connected to the study area but still it does not solve the water supply problem; hence other alternative is needed in order to supplement for existing. Various groundwater exploration programs that have been carried out in the study area have not yielded the required results. However, there was no academic research on groundwater in the study area. VES has been carried out in order to investigate groundwater potential, to determine the lithology, the resistivity value associated with the groundwater and prospect locations for groundwater exploration. The ABEM Terrameter SAS 4000 was used and a Schlumberger array was employed to accomplish this task by obtaining resistance of 7 VES points in the study area with a maximum current electrode spacing (AB) of 240 m. The VES data obtained were processed using IPI2Win software. The VES results in correlation with the and borehole log data have revealed that the near-surface materials with resistivity value between about 1 Ωm to 7,985 Ωm is representing 4 to 5 layers consisting of first layer mostly top soil and laterite, having resistivity values between 403 Ωm to 7,985 Ωm with thickness from 0.498 m to 1.21 m; second layer with resistivity values from 43.6 Ωm to 114.4 Ωm having thickness from 1.34 m to 4.71 m interpreted commonly as sandy clay and sandy soil; third layer showing resistivity values between about 1 Ωm to 38.4 Ωm is found to be a saturated layer with water; fourth layer generally indicating weathered basement with resistivity values from about 1 Ωm to 7.57 Ωm having thickness of 36.1 m and or infinite thickness, and fifth layer showing vary low resistivity value with infinite thickness. The result shows that the groundwater exploration should be conducted at VES 1, 2, 3, 4, and 5 at a depth from about 30 m to 50 m revealing low resistivity values ranging from 2 Ωm to 391 Ωm however, VES 6 and 7 indicates high resistivity value and therefore poor groundwater potentials.

Analysis of the Coal Spontaneous Combustion Risk Space Evolution in the Goaf Under Ventilation and Extraction Coupling

ABSTRACT The risk of coal spontaneous combustion in goaf is one of the disasters in coal mining, ventilation and extraction often aggravate air leakage from the goaf. Due to the unclear rule of expansion law and air leakage, the risk space for coal spontaneous combustion continues to occur. To investigate the influence of ventilation and extraction on the evolution of the risk space of coal spontaneous combustion (CSC) in goaf, further reveal the characteristics of air leakage and extraction in goaf and obtain the expansion law of CSC risk space. A three-dimensional model of goaf under surface drilling and gas extraction was developed. Using FLUENT numerical simulation software, taking a coal mine in Anhui Province, this study analyzes the influence factors, evolution law, and influence characteristics of CSC through field observations and numerical simulation. The research indicates that ventilation keeps the risk space of CSC expanding. The extraction of single drilling showed a local space expansion, while the extraction of double drilling shows the overall space expansion of the goaf. The air leakage flow path in goaf, air flow velocity vector in working face, gas concentration loss, and gas extraction characteristic parameters are determined. The loss of air leakage along the working surface meets four-stage: “strong in – flow - mixed flow – steady inflow – sudden outflow.” It can be determined that the extraction intensity of single drilling should be greater than 34.8 m3/min, and the double drilling should be greater than 18.7 m3/min. The relationship between the coupling influence of ventilation and extraction and the expansion law of CSC risk space is determined, and the maximum risk space width of CSC can be predicted. The research results are of guiding significance for CSC prevention and gas efficient extraction.

Climate change necessitates a change in the cultivation date of caraway ( Carum carvi L.)

By 2050, global crop demand is projected to rise by 60–110%. Crop yields have also been impacted by climate change in some nations, and these impacts are likely to continue. To prevent the influence of climate change on crop output, it is critical to adjust planting times in weather-related open fields to meet food security concerns. Present study was carried out at Experimental Farm of Faculty of Agriculture, Al-Azhar University, Assiut, Egypt, during two successive seasons, 2019 and 2020. It was aimed to study the effect of different sowing times (1st and 15th October, 1st and 15th November), and plant spacings (25, 20, and 15 cm) on growth, fruit yield, and oil production of caraway ( Carum carvi L.) plants. The results showed that sowing caraway plants on 15th October with plant spacing of 25 cm gave the highest dry weight (72.6 g∙plant –1), fresh weight (266.15 g∙plant –1), seed yield (37.43 g∙plant –1), and oil yield (0.659 cm3∙plant –1). The maximum umbels (50.83 number per plant) and essential oil (1.78%) were also recorded in the plants receiving same treatment. On the other hand, plants sown at 15th November with spacing of 15 cm exhibited the minimum values of recorded traits. While the highest value of plant height gave with sowing caraway plants on 15th October with plant spacing of 15 cm (135.35 cm). In conclusion, the plants sowed on October 15th with a maximum plant spacing of 25 cm had the highest values of the evaluated morphological, biochemical, and yield attributes of caraway.

Mechanical Characteristics of the Combination System of Medium-Diameter Anti-Slide Piles and Tunnel-Under-Landslide Loading

Landslides have significant impacts on the stress and deformation of existing tunnel that can damage the existing tunnel lining structures and thus affect normal traffic operation. It is of importance to study the mechanical mechanism of tunnel–landslide support systems. However, there are few studies on the mechanical mechanism of existing tunnels in landslide areas. The combination of medium-diameter anti-slide piles (300 mm ≤ D ≤ 800 mm) overcomes the disadvantages of the complex construction process and higher site requirements for large-diameter anti-slide piles (D &gt; 800 mm) and the disadvantage of lower support with micro anti-slide piles (D &lt; 300 mm). In this study, considering the influence of landslides on existing tunnel deformation, a new type of medium-diameter anti-slide pile reinforcement system for existing tunnels is proposed based on the Nanping Tunnel project. In order to study the influence of pile spacing on tunnel support, first, the maximum pile spacing of 12.5 d (25 cm) was calculated by the mathematical geometric method, and then, three physical models were established for experimental comparison and analysis, including three different spacing cases of 7.5 d (15 cm), 10 d (20 cm), and 12.5 d (25 cm). In addition, numerical simulation was used to analyze the landslide and tunnel deformation under three pile spacing working conditions. The following conclusions are reached: As the distance between the combined pile increased, the deformation of the pile body and the tunnel lining structure also increased gradually, and the earth pressure and bending moments acting on the tunnel and the pile body increased progressively. However, when the pile spacing was increased from 7.5 d to 10 d, the increase in tunnel bending moment (52.9% increase in tunnel lining moment) was much more significant than when the pile spacing was increased from 10 d to 12.5 d (28.1% increase in tunnel lining moment). The results showed that if the landslide thrust is small, the pile spacing can be increased to 12.5 d or more in the design of combined medium-diameter anti-slide piles; if the landslide thrust is large, the pile spacing should be reduced to 7.5 d or less. Whether the landslide’s thrust is large or small, the combined medium-diameter anti-slide piles with a 10 d pile spacing are less cost-effective for landslide control. The new combined medium-diameter anti-slide piles have high loading capacity and stability, which can further improve the strength of existing tunnels.

STUDI POTENSI AIR TANAH MENGGUNAKAN METODE GEOLISTRIK KONFIGURASI SCHLUMBERGER DAN WENNER DI KAMPUNG NAMBON KABUPATEN JAYAPURA

Kampung Nambon is a village in Jayapura regency which has no access to clean water. Groundwater is an alternative water source for villages which are prone to surface water sources. Groundwater aquifers are porous and permeable subsurface layers which can hold and transmit groundwater. Geoelectric method is a common geophysical method for groundwater exploration due to direct relationship between resistivity and water content. The objective of this study is to characterize subsurface structure of Kampung Nambon and to estimate the depth of potential groundwater aquifer using Vertical Electrical Sounding (VES) of Schlumberger array and Electrical Resistivity Tomography (ERT) of Wenner array. An ERT line of 100 metres whose midpoint is the sounding point of VES with maximum electrode spacing (AB/2) of 250 metres were performed. The results show that subsurface at Kampung Nambon is heterogeneous with significant lateral variation where karst formation was estimated at depth range of 5 – 15 meters. This karst formation might contain groundwater flow as indicated by relatively low resistivity values compared to high resistivity background of Limestone from Jayapura formation (Qpj).

Evaluating large delay estimation techniques for assisted living environments

Phase wraparound due to large inter-sensor spacings in multi-channel demixing limits the range of relative delays that many time–frequency relative delay estimators can estimate. The performance of a large relative delay estimation method, called the elevatogram, is evaluated in the presence of significant phase wraparound. This paper compares the elevatogram with the popular relative delay estimator used in DUET and the brute-force approach in D-AdRess and analyses its computational efficiency. The elevatogram can accurately estimate relative delays of speech signals of up to 800 samples, whereas DUET and D-AdRess were limited to delays of 7 and 35 samples, given a sampling rate of 16 kHz. Monte Carlo trials on 1000 real speech utterances show that the Matlab execution time of the elevatogram is slower than DUET, however it can accurately estimate delays that are 100-times greater than DUET. Source separation algorithms that use time–frequency relative delay estimators may be extended to function with maximum inter-sensor spacings of greater than 2.5 cm.

Descriptions of the dynamic joint space of the temporomandibular joint

BackgroundClinical diagnosis and treatment depended heavily on the motion analysis of the human joints. Although the dynamic joint space (DJS) of other organs was widely used in academic investigations, they were not universally used in the temporomandibular joint (TMJ) field, which was also important for the motion evaluation of the TMJ. The objectives of this study are to introduce the DJS of the TMJ and characterize the DJS regulars of mandibular movements. MethodsTen asymptomatic subjects were selected to instruct this application. The mouth opening and closing, mandibular protrusion, and left and right protrusions, were tracked by the optical motion tracking system. According to trajectories of markers and reconstructed models from computed tomography, the motions of the mandibles could be obtained. The DJSes, which were described as the minimum Euclidian distances, were subsequently calculated based on the geometrical surfaces between the condyle and fossa during the motions. Then, the DJS map could be drawn based on the calculated values. ResultsThe DJS map manifested a decreasing trend when the condyle crossed the glenoid fossa, while it generally increased after the condyle crossed the fossa during the mouth opening. The results showed that the average maximum and minimum anterior joint spaces were 5.39 mm and 2.07 mm during mouth opening respectively with a great discrepancy existing among the subjects. The average maximum and minimum anterior joint spaces were 4.74 mm and 2.19 mm during mandibular protrusion. As for left and right protrusions, the DJS of the contralateral side was greater than that of the ipsilateral side. ConclusionIn comparison to morphological analyses or only mandibular motions, the DJS provides more dynamic and interactive information about the TMJ. The research and methodology may help us comprehend TMJ motions and temporomandibular disorders.

A distributed model predictive control method combined with delay compensator for multiple vehicle platoons

With an increasing number of vehicles on the road, multiple-vehicle platoons have become a new solution under communication constraints. However, the existing studies seldom consider the effect of the tail vehicle on the information transfer and platoon control over long distances, and thus the control performance under time-varying delays is unacceptable. In this study, a hierarchical multi-platoon control architecture considering the backbone platoon and sub-platoons is proposed under non-ideal communication conditions, where the backbone platoon layer communication topology is designed to achieve backbone platoon control and appropriate coordination among sub-platoons. Distributed model predictive controllers (DMPCs) for backbone- and sub-platoons that integrate delay compensation have been proposed. Buffers and delay compensators in the proposed DMPC are designed to reduce the interference caused by non-ideal communications. The asymptotic stability is analyzed at the sub- and multi-platoon levels. The results show that compared with traditional DMPC without a compensator, the proposed DMPC can eliminate the velocity lag and steady-state spacing errors and maintain the maximum velocity and spacing errors within 0.11 m/s and 0.17 m, respectively, under certain operating conditions. Thus, the proposed method guarantees the stability of multiple platoons under both the constant and time-varying delay conditions.

Evaluation of aquifer hydraulic conductivity and transmissivity of Ezza/Ikwo area, Southeastern Nigeria, using pumping test and surficial resistivity techniques.

Aquifer hydraulic parameters including hydraulic conductivity and transmissivity play a very important role in the assessment and management of groundwater. Conventionally, these parameters are best estimated employing pump test, which is usually expensive and time-consuming. The use of surficial electrical resistivity data integrated with few available pumping test data provides a cost-effective and efficient alternative. A total of thirty-five (35) vertical electrical soundings with a maximum half-current electrode spacing of 150m using the Schlumberger array were used in this study. Five (5) of these soundings were parametric soundings carried out in the vicinity of monitoring wells for correlation and comparative purposes. The empirical relationships between the hydraulic parameters derived from the pump test data and the aquifer resistivity data were established for the Ebonyi and Abakaliki Formations, respectively, and, in turn, used to estimate aquifer hydraulic parameters in areas away from wells. Aquifer hydraulic conductivity estimated across the study area varies from 0.49 to 1.5735m/day with a mean value of 0.9205m/day for the Ebonyi Formation, while the Abakaliki Formation has hydraulic conductivity values that vary from 0.0775 to 1.3023m/day, with a mean value of 0.2883m/day. The transmissivity values estimated across the study area range between 0.29 and 57.27 m2/day with a mean value of 6.59 m2/day. Transmissivity values obtained were interpreted with Krásný's transmissivity classification, and this delineated the study area into three groundwater potential zones: very low, low, and intermediate zones. The study shows that the areas underlain by the Ebonyi Formation have a higher groundwater potential than those underlain by the Abakaliki Formation. These findings are supported by the geology of the area, which revealed that the Abakaliki Formation is dominated by shales with very low permeability, while the Ebonyi Formation consists of shales with alternations of sand/sandstones, which statistical analysis of the different model equations used in estimating the hydraulic parameters of the study area revealed that the new model empirical equations proposed and used in the present study proved to be the best alternatives to pumping test data.

LiDR: Visible-Light-Communication-Assisted Dead Reckoning for Accurate Indoor Localization

Pedestrian dead reckoning (PDR) is an inertial navigation system that relies on smartphone sensors for estimating a pedestrian’s step movements. However, such systems suffer from poor accuracy due to the drift and inherent noise in sensor readings. In addition, step size variation among pedestrians and device heterogeneity pose further challenges for building a scalable PDR system that can provide uniform performance across various devices and a diverse range of users. Visible light positioning (VLP), which uses LED lights with visible light communication (VLC) capability to provide high-accuracy localization, can achieve precision of a few cm. However, VLP systems suffer from practical limitations due to occasional line-of-sight (LOS) blockage and the sparse density of lighting in large-scale indoor venues. In this work, we propose a light-assisted dead reckoning (LiDR) system, which aims to address the problems of both VLP and PDR. It uses LED lighting as high-accuracy location landmarks to provide regular calibration for the PDR and estimates the individual pedestrians’ step size for increased accuracy. In addition, a light-shape-based heading angle correction algorithm is proposed to reduce the heading angle error and further improve the accuracy. The system is implemented as an Android-based navigation application, with a digital map and cloud-based backend storage for location, device, and user-specific parameters. The real-time performance of the system is evaluated in a 450- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{m}^{2}$ </tex-math></inline-formula> lab and on a 150-m walking track. The experimental results demonstrate that with a maximum light spacing of 15 m, an overall average accuracy of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lt ~0.7$ </tex-math></inline-formula> m can be achieved for the whole system.

Dimensioning Aids for Stiffened and Unstiffened Plates According to Eurocode 3 Part 1‐5

AbstractIn Germany stiffened plate in bridge construction must be verified using the method of reduced stresses (MRS) according to DIN EN 1993‐1‐5 [2, 3]. Unstiffened plates on the other hand may be verified either according to the effective widths method or according to the reduced stress method. In order to shorten the time‐consuming verification of the standardised verification formats for pre‐dimensioning which is particularly prevalent for stiffened plates diagrams are developed and presented in the present paper on the basis of the MRS by reformulating the buckling verification which enable a quick pre‐dimensioning. With the diagrams, the dimensioning of plate thicknesses and stiffener spacings can be carried out in a few simple and comprehensible steps. The diagrams are selected on the basis of the geometry parameters .a, b. and t or the applicable boundary conditions. For stiffened plate, the maximum permissible spacing of the longitudinal stiffeners or the required main plate thickness can be determined. Diagrams for the dimensioning of longitudinal stiffeners by determining minimum stiffnesses are also presented. The minimum stiffnesses are derived from the geometry of the linear buckling shapes of simply stiffened plate.