Separate Grids Research Articles

Influence of a Separation Grid on the Efficiency of Particulate Matter Capture in a Device with Arc-Shaped Elements

Influence of a Separation Grid on the Efficiency of Particulate Matter Capture in a Device with Arc-Shaped Elements

Technical Evaluation of Photovoltaic Systems in the Bamenda Municipality of the North West Region of Cameroon

In the Bamenda Municipality of Cameroon households are adopting Solar Photovoltaic Systems (SPVS). The penetration of SPVS in this Municipality depends on their technical performance. The study aimed to evaluate the technical installation of SPVS within the Municipality. A field inspection and administration of a questionnaire was conducted. The field inspection evaluated the respect of technical installation norms for SPVS. The questionnaire captured data on the technical situation of the SPVS. The SPVS installed included PV and grid to power separate loads, and PV and grid to power same loads. The installed loads were a mix of AC and DC loads of capacity from 360 W to 10000 W. The load powered by the installed SPVS varied from 300 W to 7000 W. The PV array varied from 200 W to 3200 W and battery bank capacity of 100 Ah to 800 Ah. The PV arrays were mostly installed on roof tops. Only 5% of the SPVS were installed by certified personnel. More than 50% of the installed SPVS operated below designed operation time. Failures in installed systems were related to inverters (36 %) and battery banks (36 %). Most of the PV arrays were installed on rooftops at tilt angles between 20° and 50°. More than 50 % of the PV arrays were oriented to directions other than South. Protective devices were installed in only 14 % of the installed systems. Some of the SPVS were not properly dimensioned. It may be concluded that most of the installed SPVS do not respect the technical installation norms and were not dimensioned according to users’ needs. The survival and penetration of SPVS technology in the Bamenda Municipality, Cameroon, and other sub-Saharan communities requires awareness and capacity building, policies, and regulations in the design and installation of this technology.

Optimizing separate and combined grids for cost-effective hybrid renewable energy electrification in Mogadishu, Somalia

Expanding access to affordable, reliable, and sustainable electricity is an urgent priority in Somalia, which suffers from high energy costs and climate vulnerability despite negligible emissions. Therefore, this study employs MATLAB simulation software and three algorithms—particle swarm optimization (PSO), genetic algorithm, and simulated annealing—to determine optimal separate and combined grid designs for a hybrid renewable energy system in Mogadishu, Somalia. Four system configurations are assessed, namely, utilities—diesel-alone, Photovoltaic (PV)–diesel hybrid, wind–diesel hybrid, and PV–wind–diesel hybrid across the grids of three utilities—Benadir Electric Company, Mogadishu Power Supply, and Blue-Sky Energy. The algorithms evaluate technical feasibility, economic viability, and system reliability to identify the most suitable configurations. Forty-eight systems are analyzed. The combined PV/wind/diesel grid optimized with PSO is most effective, reducing the net present cost by 32%–47% and levelized cost of electricity by 41%–60% compared to diesel-only systems while maintaining reliability. Greenhouse gas emissions decrease by 38%–59% with the hybrid system.

Power Scheduling Optimization Method of Wind-Hydrogen Integrated Energy System Based on the Improved AUKF Algorithm

With the proposal of China’s green energy strategy, the research and development technologies of green energy such as wind energy and hydrogen energy are becoming more and more mature. However, the phenomenon of wind abandonment and anti-peak shaving characteristics of wind turbines have a great impact on the utilization of wind energy. Therefore, this study firstly builds a distributed wind-hydrogen hybrid energy system model, then proposes the power dispatching optimization technology of a wind-hydrogen integrated energy system. On this basis, a power allocation method based on the AUKF (adaptive unscented Kalman filter) algorithm is proposed. The experiment shows that the power allocation strategy based on the AUKF algorithm can effectively reduce the incidence of battery overcharge and overdischarge. Moreover, it can effectively deal with rapid changes in wind speed. The wind hydrogen integrated energy system proposed in this study is one of the important topics of renewable clean energy technology innovation. Its grid-connected power is stable, with good controllability, and the DC bus is more secure and stable. Compared with previous studies, the system developed in this study has effectively reduced the ratio of abandoned air and its performance is significantly better than the system with separate grid connected fans and single hydrogen energy storage. It is hoped that this research can provide some solutions for the research work on power dispatching optimization of energy systems.

A WAVEWATCH III® model approach to investigating ocean wave source terms for West Africa: Non-linear wave-wave interaction source terms

• Investigation of ocean wave model parameterization schemes for West Africa. • Selection of appropriate non-linear source terms for ocean wave projections. • DIA term best estimates wave heights for sub-sections of West Africa. • Application of no non-linear term best estimates wave heights for the entire region. Ocean wave forecasting for West Africa has mostly relied on global parameterization schemes and data outputs. Investigating non-linear ocean wave-wave interaction source terms ( S nl ) for the region, that forms part of the wave model parameterization schemes, is a contribution of this study towards developing a regional wave modelling scheme for West Africa. The study evaluates five non-linear source term configurations with the WAVEWATCH III® (WW3) numerical ocean wave model version 5.16; (i) No source term applied - NL0, (ii) Discrete Interaction Approximation (DIA) – NL1, (iii) Exact Interaction Approximation – NL2, (iv) Generalized Multiple DIA – NL3, and (v) Two-Scale Approximation – NL4, in order to determine best performing S nl for projecting significant wave heights and directions for the region. The wave simulations were run on three separate grids comprising a low resolution West Africa grid (latitudes 10 o S – 30 o N; longitudes 35 o W – 15 o E), high resolution south-eastern (latitudes 2 o S – 8 o N; longitudes 10 o W – 10 o E) and north-western (latitudes 10 o N – 25 o N; longitudes 30 o W – 10 o W) sub-grids. Simulations for the entire West Africa grid produced higher accuracies for the wave parameters compared to the higher resolution sub-grids. NL0 best estimates significant wave height whereas NL3 best estimates wave directions for the West Africa grid. For combined stations of the south-eastern sub-grid, while NL1 best estimates wave heights, NL3 best estimates the wave directions with possible alternation with NL1 due to insignificant differences. Similarly, for the north-western sub-grid, while NL1 best estimates significant wave heights, NL0 best estimates wave directions with similar ability to alternate with NL2 in projecting wave directions. Generally, insignificant differences exist between the source terms in projecting wave directions, especially for the north-western sub-region, implying that any of the source terms may be used in projecting wave directions without significantly compromising on accuracy. Thus, NL1 which best estimates significant wave heights for both south-eastern and north-western sub-regions can also be used in estimating the wave directions. Similarly, NL0 would be appropriate for the entire West Africa region.

The no-wait cyclic scheduling of delivery traffic in the grid distribution network

This paper presents a method for the fast prototyping of no-wait cyclic schedules for periodic material handling systems with a Grid-like Material Transportation Network (GMTN). A distribution network is modeled as a grid-like system of cyclic processes performing regular pick-up and delivery operations between workstations in separate grid modules. The considered problem boils down to a job shop cyclic scheduling problem with no-buffer and no-wait constraints, which is NP-hard. The main contribution of this research is a novel method of grid-like system decomposition into subsystems with two processes using one common resource and construction of the necessary and sufficient conditions for the existence of a no-wait cyclic schedule (N-WCS) of the system for given start times of the processes. The approach’s novelty involves implementing a linear-complexity procedure, which allows quick testing of whether any N-WCS may exist. Due to the low computational complexity of the procedure, it is possible to determine the start times of processes initiation for delivery networks of the scale encountered in practice and calculate corresponding cyclic schedules. A set of initial states of no-wait cyclic schedules (N-WCSs) for the systems with a grid structure of arbitrary dimensions is determined based on computational examples.

Optimal Power Flow Through Variable Frequency Transformer Using Different Optimization Techniques

For synchronous and asynchronous connectivity of separate power grids, phase shifting transformers (PST), the high-voltage-direct-current (HVDC) converters and variable-frequency-transformer (VFT) are viable options. Natural damping and high overloading capabilities are inherent in the VFT, which is critical for power grid reliability and stability. This article reports the optimal power flow across a power system involving the implementation of several meta-heuristic optimization techniques based control strategy. Several optimization techniques are applied to optimize the gains of proportional-integral-derivative (PID) controller which aids in regulating the system dynamic response. The firefly algorithm based PID controller performs better in contrast to other optimization techniques in improving the system dynamics. The DC motor accustomed with PID controller provides the required torque necessary for power transfer between two connected grids. Sensitivity analysis is exhibited to inspect the strength of developed power system against deviations in certain system parameters. A separate study is done for the asynchronous operation of VFT based power system using firefly algorithm with different DC motor torque. To validate the effect of VFT over HVDC total harmonic distortion analysis has been carried out to check for the harmonic content in the rotor and stator current of VFT.

Quasi Single-Stage Three-Phase Filterless Converter for EV Charging Applications

This paper presents a novel converter concept of the off-board electric vehicle (EV) charging, which is based on an unfolding rectification approach where the three-phase Vienna rectifier-based unfolder (VRU) is followed by two identical isolated current-source converter (CSC) modules in input-series output-parallel configuration. The VRU operates at low frequency and thus features negligible switching losses, while the CSCs are responsible for the synthesis of the high-quality sinusoidal grid current and output voltage regulation. The proposed configuration features two time-varying soft DC-links, thus no bulky electrolytic capacitors are required. Input inductors of the CSCs limit the input current ripple, eliminating the need for separate grid filter inductors. Another notable advantage lies in the simplicity of the control system. Each CSC operates at a fixed frequency and provides the required current wave-shaping using only a single independent control variable, while no high-frequency synchronization between the two modules is required. The proposed configuration features a modular structure and was verified with a 5 kW experimental prototype based on two identical 2.5 kW dc-dc modules and a common unfolding stage. During the experiments, the system provided power factor above 0.97 and THD below 5%. At rated power, the maximal efficiency of 94.8% was obtained.

Compact, self-aligned focusing schlieren system.

A novel, to the best of our knowledge, compact, self-aligned focusing schlieren system is presented that eliminates the need for a separate source grid and cutoff grid. A single grid element serves both to generate a projected source grid onto a retroreflective background and act as the cutoff grid for the reflected light. This is made possible by manipulating the polarization of light through the system. The use of only a single grid element eliminates the need to create a cutoff grid that is perfectly matched and scaled to the source grid, and removes the need to align the source and cutoff grids to each other. The sensitivity to density objects is adjustable with the use of a polarizing prism. Images obtained with this system show operation similar to existing focusing schlieren systems, but with much reduced complexity and setup time. Images taken with acrylic windows placed normal to the optical axis further demonstrate the system's utility for wind tunnel measurements.

Inverse ray tracing on icosahedral tetrahedron grids for non-linear laser plasma interaction coupled to 3D radiation hydrodynamics

A novel approach to efficiently model 3-D laser plasma interactions at fluid scales is presented. This method, implemented in the IFRIIT propagation code developed at CELIA, relies on inverse ray tracing to compute laser fields at arbitrary locations in a plasma. This enables to describe the fields at high order in space compared to standard forward ray tracing approaches. In addition, inverse ray tracing enables the use of etalon integral methods to reconstruct caustic fields and greatly speeds up calculations of cross-beam energy transfer by decoupling the ray amplitude and ray phase calculations. A comparison of the inverse and forward methods for 3-D calculations of fields in presence or not of cross-beam energy transfer illustrates the significant advantages of the inverse method. Conversely, while the inverse method is well suited to most spherical plasma profiles, it currently cannot treat concave profiles or target holders. The coupling of IFRIIT with the 3-D ASTER radiative hydrodynamics code developed at the Laboratory for Laser Energetics is then presented. ASTER and IFRIIT resolve their respective equations on separate grids which communicate through interpolation. As such, IFRIIT uses a dedicated laser grid adapted to the computations at play, which also allows to use different parallelization methods for both codes: block decomposition for the hydrodynamics versus domain duplication for the laser. Applications to direct-drive implosions for inertial confinement fusion are presented, for which a geodesic icosahedron grid is implemented in IFRIIT. The performances of the ASTER/IFRIIT coupling are demonstrated by conducting simulations of cryogenic implosions performed on the OMEGA laser system, in presence of various sources of 3-D effects; laser port geometry, cross-beam energy transfer, beam imbalance and target mis-alignment. Comparison with neutron data, measured through bang-time, for a cryogenic implosion experiment shows an excellent agreement for the laser-plasma coupling.

PATHOLOGIES OF THE ELDERLY AND PHARMACOTHERAPY IN THE HEALTH AREA OF BIWONG-BANE, SOUTH CAMEROON

Objectives: The specific characteristics of the elderly physiopathology, such as polypathology and polypharmacy, arouse interest in the quality of the care offered to this age group. The study aimed to analyse the gap between the pathological and therapeutic profiles at the local level in Cameroon. Method: This was a six-month cross-sectional situational analysis at the Biwong-Bane District Medical Centre in the South region of Cameroon. Pathological data were collected from the consultation register, and those related to therapeutics were taken from the drug inventory lists for the period of July 2019 to July 2020, using two separate reading grids. The 20th version of Statistical Package for the Social Sciences software was used for the analysis of the data set. Results: For a total of 103 patient files, the mean age was 68.6±7.7 years with a sex ratio of 0.75. 21.7% of the population was aged ≥ 75 years. The main pathology groups were infectious diseases (40%) and diseases of the osteoarticular system (16.4%). Out the 140 occurrences counted, malaria, typhoid fever and high blood pressure were the most common at 26, 12 and 7 respectively. Polypathologies represented 28.2% of the sample. With regard to therapeutics, there was a concordance between prescriptions and available drugs, although stock-outs persisted, as with artesunate (10 months) and mineral supplements (6 months). Finally, the average number of active molecules administered per elderly person ≥75 years was 3.47. Conclusion: The pharmacotherapy provided to the Third age remains poorly adapted, mainly due to the unavailability of drugs specific to the needs of this population. Peer Review History: Received 22 March 2021; Revised 16 April; Accepted 26 April, Available online 15 May 2021 UJPR follows the most transparent and toughest ‘Advanced OPEN peer review’ system. The identity of the authors and, reviewers will be known to each other. This transparent process will help to eradicate any possible malicious/purposeful interference by any person (publishing staff, reviewer, editor, author, etc) during peer review. As a result of this unique system, all reviewers will get their due recognition and respect, once their names are published in the papers. We expect that, by publishing peer review reports with published papers, will be helpful to many authors for drafting their article according to the specifications. Auhors will remove any error of their article and they will improve their article(s) according to the previous reports displayed with published article(s). The main purpose of it is ‘to improve the quality of a candidate manuscript’. Our reviewers check the ‘strength and weakness of a manuscript honestly’. There will increase in the perfection, and transparency. Received file: Reviewer's Comments: Average Peer review marks at initial stage: 6.0/10 Average Peer review marks at publication stage: 7.0/10 Reviewer(s) detail: Dr. Omid Gholami, Sabzevar University of Medical Sciences, Iran, omidghphd@gmail.com Dr. DANIYAN Oluwatoyin Michael, Obafemi Awolowo University, ILE-IFE, Nigeria, toyinpharm@gmail.com

Development of Groundwater Irrigation in Telangana State: Challenges, Management and Way Forward

Groundwater based irrigation, which was started in India as early as “Indus Civilizations” got impetus during 3rd five-year plan. In India, at present 78 m ha of irrigation potential is created and 80 percent is utilized. One of the World’s highest user of groundwater is India with 63 percent of its dynamic groundwater resources. Similarly, Telangana State is also utilizing the dynamic groundwater resources up to 65 percent. Groundwater a reliable source of irrigation with high yields and brings equity among its users as ∼99 % of structures are owned by individuals. In the state, well irrigation increased from ∼0.46 lakh ha from 1875 to 23.35 lakh ha during 2017–18 and well density increased to ∼13 wells/km2 leading to decrease in irrigation potential under each well to < 1 ha. As a result of it many challenges like water logging & salinity in canal command areas, over-exploitation leading to de-saturation of shallow aquifers, underutilization in north eastern part, groundwater pollution (both geogenic and anthropogenic) and sustainability, etc have cropped up. The management steps taken up in water sector like water transfer through KLIP, providing protected water supply through Mission Bhagiratha, de-siltation through Mission Kakatiya, forest rejuvenation through Haritha Haram, construction of various ARS, modernization of canals, conjunctive use of surface and groundwater, user centred aquifer level groundwater management, tank management, IEC activities etc brought positive changes in water availability in the state more particularly surface water. In order to sustain these efforts, formation of WUA at watershed/village level for agricultural planning, change in cropping pattern from highly intensive paddy to ID crops more particularly from non-command areas, conjunctive use of water, warabandhi (on/off) method of releasing irrigation water, developing intercepting drains, soil treatment, declaring crop holidays, separate electric grids for agriculture and domestic supply, legally separating water and land rights and strict implementation of regulatory measures. The other measures suggested are policy interventions that involve regulatory mechanisms and linking village-based institutions to government departments that manage groundwater etc.

Ion Acoustic Peregrine Soliton Under Enhanced Dissipation

The effect of enhanced Landau damping on the evolution of ion acoustic Peregrine soliton in multicomponent plasma with negative ions has been investigated. The experiment is performed in a multidipole double plasma device. To enhance the ion Landau damping, the temperature of the ions is increased by applying a continuous sinusoidal signal of frequency close to the ion plasma frequency ∼1 MHz to the separation grid. The spatial damping rate of the ion acoustic wave is measured by interferometry. The damping rate of ion acoustic wave increases with the increase in voltage of the applied signal. At a higher damping rate, the Peregrine soliton ceases to show its characteristics leaving behind a continuous envelope.

Application of the immersed boundary method in solution of radiative heat transfer problems

The immersed boundary method (IBM) was developed for the first time in the present study to simulate the radiative heat transfer problems in complex geometries. The pseudo time stepping technique was applied to solve the radiative transfer equation (RTE) using the finite volume method (FVM). Also, the direct forcing-sharp interface was used in IBM. This method was validated with some benchmark problems in two states of pure radiative and combined radiative-conductive heat transfer. Then, the effects of the conduction-radiation parameter and absorption coefficient on heat flux distribution and isotherms were investigated in an enclosure with inner complex bodies. The results indicated that this method acts well in solving the radiative heat transfer problems in complex geometries. Also, due to using unique Eulerian and Lagrangian grids for solving the energy and radiative transfer equations, production of a separate grid is not required in solving combined heat transfer problems. This is one of the most significant features of the presented method.

Radial control of electron temperature gradient with optimized operational configuration of double plasma device

A double plasma device (DPD) is tested for different operational configurations to identify suitable control for plasma parameters in a weakly ionized, unmagnetized plasma discharge. A separation grid is installed between the two chambers of DPD, which allows filtering of plasma from the first to the second chamber. Investigations are carried out to control the plasma parameters, especially the electron temperature by exploring the role of the grid. The grid bias is varied between −25–0 V and 0–30 V to reflect cooling and heating of plasma. The electron heating and cooling is prominent for the maximum ratio of n source/n target. The electron energy distribution function (EEDF) is obtained to describe the role of grid biasing in controlling the electron temperature in the second chamber. We demonstrated control on the radial profile of electron temperature by charging different radial cross-sections of plasma differently by using a multi-grid assembly system (MGAS). We have also identified the suitable operational regime for DPD where exercising a radial control on electron temperature is possible. Such plasmas can facilitate investigations on electron temperature control for applications in plasma processing, cold–plasma material interaction, etc where low energy electrons are desired.

Implementation of a stable high-order overset grid method for high-fidelity simulations

The implementation of an overset grid method into a compressible in-house computational fluid dynamics solver is described. The framework employs a novel algorithm for the generation of the composite grid, i.e. to identify the discretisation, interpolation and non-physical points. This algorithm was designed to minimise and simplify the user input, while maintaining the flexibility to handle complex setups. An explicit fourth-order Lagrange interpolation scheme is used, so that the formal order of accuracy of the finite difference scheme used in the flow solver is matched. An instability linked to the possible presence of uncoupled numerical solutions on separate grids sharing the same physical location is discussed, and a modification of the composite grid generation algorithm that prevents this instability is introduced. The final overset grid method is validated with two test cases: the convection of an isentropic vortex and the Taylor-Green vortex.

Scenarios analysis on the cross-region integrating of renewable power based on a long-period cost-optimization power planning model

Rapid increase of renewable power brings integration challenges, such as need of system flexibility, the spatial mismatch of renewable resources and power loads, and long-term decarbonization policy uncertainty. In this study, a long-term multi-regional power system planning model is proposed with monthly, regional and sectorial demand forecast, describing fluctuation of renewable power, and optimization of installed capacity, power grids and storage facilities. The most cost-effective renewable power deployment of Southwest China is presented as a case study due to abundant renewable resources, significant monthly fluctuation and insufficient infrastructure. Scenario analysis is conducted to address policy uncertainties of carbon tax and power substitution. Results show that albeit limiting and reducing coal power is necessary, de-capacity policies cannot be implemented equally in all regions considering its ability to handle renewable power volatility. To enhance system flexibility, storage facilities are required in Sichuan and Yunnan whilst fossil power plants are required in Chongqing and Guizhou. For cross-region integrating of renewable power, two separate grids in China should be connected between Chongqing and Guizhou. Hydropower could be delivered to eastern regions to meet peak loads of summer cooling. The Southeast power exported to South regions would gradually decrease since its demand increase rapidly.

Super-interference in atomic photoionization: Moiré patterns in momentum maps

SynopsisWe theoretically investigate on the origin of lateral ring structures in the doubly differential momen-tum distribution for atomic ionization by laser pulses in the midinfrared spectral region. We demonstrate that such structures stems from the interplay between intra- and intercycle interference patterns which work as two separate grids in the two-dimensional momentum domain. When the periods of the two grids (intra- and intercycle) are similar, moiré patterns arise as concentric rings at high electron kinetic energy.

A signal screening based sequence-correlation localization algorithm for wireless sensor networks

Wireless sensor networks (WSNs) are dependent on sending and receiving signals. This work aims to design a received signal strength based range-free localization technique called signal screening based sequence-correlation localization algorithm (SCLSS) which can provide accurate and cost efficient localization performance for WSNs. Starting with the division of location region into multiple separate grids, SCLSS utilizes the grid-type measure to obtain a unique intersection-sequence table which represents the Euclidean distances from each anchor node to each grid intersection. Secondly, based on the signal screening method, SCLSS screens out the task intersections which will derive new intersections. Then the selected intersections are filtered out from the derived intersection-sequence table according to Pearson correlation. Finally, SCLSS uses the weighted centroid approach to isolate the location where the unknown node most probably resides. Simulation results show that the proposed SCLSS offers more accurate localization with fewer anchor nodes compared with its counterparts.

Bycatch reduction device in the Chilean hake (Merluccius gayi) bottom trawl fishery, using a rigid separation grid

The Chilean hake trawl fishery is one of the most emblematic fisheries in Chile. Considering the type of trawl gear used in the industrial fleet and the variety of species which cohabitates this target specie, discarding has become a recurrent practice, where the jumbo squid and the Chilean hake are often part of the discarded fauna. This problem has been monitored since the amendment of General Fisheries and Aquaculture Law in Chile in 2012, where a definition for discard was incorporated, regulations were modified and sanctions were established for those who engage in this practice. To date, the estimates of discards in this fishery have experienced a reduction from five to one thousand tons, decreasing the amount of discarded catch of Chilean hake and jumbo squid. This reduction is coincident with the introduction of the rigid separation grid in the bottom trawls of the vessels that adopted its use. This article describes the use of the rigid separation grid in trawl hauls aimed at Chilean hake, in which there were fewer hauls with the presence of jumbo squid and also reduced the capture and the catch per unit effort of this species. Besides, an experimental work, which involved the use of a cover codend to retain the fraction of escaping fish due to the use of the grid, allow to verify the jumbo squid escape. The results allow concluding that the use of this device has shown to be effective allowing the escape rate of non-target species catch, as well to posterior discards of these species.