Search

This paper introduces a novel methodology for determining wind turbines' optimal site matching. Our framework's key component is establishing four new probabilistic models to model wind turbines' capacity factors. First, we used the sum square of errors (SSE) and the determination coefficient (R2) to assess the accuracy of the proposed models. The developed models were then generalized to estimate wind farm capacity factors. After that, the proposed methodology's validity is tested by applying it to a known wind data site. We modeled the available wind data using Weibull distribution. Five different methods were used to determine Weibull parameters. The equivalent energy method combined with the invasive weed optimization algorithm yields the optimal values for these parameters. Finally, under the support of the presented models, the novel methodology is applied to a pool of 24 commercial turbines to choose the optimal ones. A comparison is made between the obtained capacity factor curves using the suggested models and other previous models for the selected wind turbines. When the presented models are utilized, the capacity factor of commercial wind turbines with non-ideal electrical power curves is more precisely predicted.

Gestational age assurance is one of the best strides in the administration of the timing of pregnancy and subsequent diminishing in perinatal mortality due to preterm conveyances. There is no single boundary to assess the gestational age. The utilization of ultrasound (US) biometric routine boundaries, including biparietal width (BPD), head outline (HC), stomach circuit, femoral length (FL), and fetal weight, is obligatory at all pregnancies beginning from 20 weeks. However, at late incubation , these boundaries are not exact. This examination expected to assess the precision of fetal kidney length by ultrasonography in assessing gestational age in third trimester. Techniques: This investigation is cross sectional examination that was done at Benha University clinic during the period from March 2019 to March 2020.Routine U/S assessment and kidney assessment. Estimations of all fetal biometric boundaries were acquired. Results: When contrasting the determined GA and LMP with various boundaries, the mean of LMP GA was (36.5±2.6), BPD GA was (36.0±2.72), HC GA was (35.8±2.70), AC GA was (35.5±2.9), FL GA was (36.5±2.73).There were measurably critical positive connection between's mean fetal kidney length and (biparietal breadth (BPD), BPD GA, head outline (HC), HC GA, stomach boundary (AC), AC GA, femoral length (FL) and FL GA. The current investigation determined a condition for assessment of the gestational age from the fetal kidney length (FKL) with SE ±2.4 days. End Fetal kidney length increments with increment in fetal gestational age (FGA) and shows incredible intra and bury class connection coefficient which recommends great understanding and reproducibility of estimations.

Flashover voltage is considered one of the important factors affect the Power system reliability. Environmental conditions and filling of insulators are parameters should be considered in flashover voltage evaluation. In this work, laboratory studies are carried out on insulator with Alumina Trihydrate [ATH] filling at different concentration and different weather conditions to investigate the flashover voltage. The evaluation of flashover voltage is carried out at three conditions dry, wet and salt wet condition. In each test, four different lengths with different filling concentration are considered. Several curve fitting methods are used to obtain an equation of flashover voltage. The obtained equation first is only function of filling at different insulator lengths with approximately zero errors. Although the accuracy of this method, it gives flashover voltage only at discrete lengths. Thus, for continuous length validation the flashover is fitted again to be a function of both length and filling.

As technology advanced, electrical interruption or disturbance still becomes a significant problem in power systems. A fault is one example of electrical disturbance or power failure in a power system. In order to recover the system, the fault must be detected, classify and locate to eliminate as fast as possible. Four types of fault occur in the transmission line. Those four types are Line-to-Ground Fault (L-G), Line-to-Line Fault (L-L), Double Line-to-Ground Fault (L-L-G), and Three Line Fault (L-L-L). These Days, fault has been one of the significant problems in the transmission line system. Fault can lead to power losses in transmission lines as well as power failure. Electrical service in the transmission line system needs to be recovered immediately after fault appears to avoid more energy losses. Thus, it is crucial to create a system that will detect and eliminate fault faster, more accurately, and effectively. Typically, transmission line fault classification required complex signal processing, required expert knowledge, and complex mathematical modeling to process the output signal. This paper proposed a deep learning technique to classify ten types of fault through simulation. The objective of this study is to propose automated signal processing and features extraction. This technique can model a system that generates the automated signal processing and extract features learning with a deep learning framework and classify all the ten fault types in transmission lines accurately and effectively.

In this paper, COVID-19 dynamics are modelled with three mathematical dynamic models, fractional order modified SEIRF model, stochastic modified SEIRF model, and fractional stochastic modified SEIRF model, to characterize and predict virus behavior. By using Euler method and Euler-Murayama method, the numerical solutions for the considered models are obtained. The considered models are applied to the case study of Egypt to forecast COVID-19 behavior for the second virus wave which is assumed to be started on 15 November 2020. Finally, comparisons between actual and predicted daily infections are presented.

As wind turbines more widely used with newer manufactured types and larger electrical power scales, a brief mathematical modelling for these wind turbines operating power curves is needed for optimal site matching selections. In this paper, 24 commercial wind turbines with different ratings and different manufactures are modelled using single cumulative probability density functions modelling equations. A new mean of a composite cumulative probability density function is used for better modelling accuracy. Invasive weed optimization algorithm is used to estimate different models designing parameters. The best cumulative density function model for each wind turbine is reached through comparing the RMSE of each model. Results showed that Weibull-Gamma composite is the best modelling technique for 37.5% of the reached results.

Deep Learning has ignited great international attention in modern artificial intelligence techniques. The method has been widely applied in many power system applications and produced promising results. A few attempts have been made to classify fault on transmission lines using various deep learning methods. However, a type of deep learning called Long Short-Term Memory (LSTM) has not been reported in literature. Therefore, this paper presents fault classification on transmission line using LSTM network as a tool to classify different types of faults. In this study, a transmission line model with 400 kV and 100 km distance was modelled. Fault free and 10 types of fault signals are generated from the transmission line model. Fault signals are pre-processed by extracting post-fault current signals. Then, these signals are fed as input to the LSTM network and trained to classify 10 types of faults. The white Gaussian noise of level 20 dB and 30 dB signal to noise ratio (SNR) is also added to the fault current signals to evaluate the immunity of the proposed model. Simulation results show promising classification accuracy of 100%, 99.77% and 99.55% for ideal, 30 dB and 20 dB noise respectively. Results has been compared to four different methods which can be seen that the LSTM leading with the highest classification accuracy. In line with the purpose of the LSTM functions, it can be concluded that the method has a capability to classify fault signals with high accuracy.

Masquerade presentation of acute type B aortic dissections (TBAD) as acute limb ischaemia (ALI) is rare. Holistic clinical assessment, preferably with the help of scoring systems and timely computer tomographic angiogram (CTA), is needed for early diagnosis. Acute TBAD and its complications are increasingly treated with endovascular therapies.A 21-year-old male with poorly controlled essential hypertension was admitted with prominent clinical features of ALI. No clinical pointers of a TBAD were present. Doppler ultrasound revealed an arterial occlusive pattern, and an urgent surgical embolectomy was performed. On failure to retrieve any thrombi, a CTA was performed, and diagnosis of TBAD complicated with ALI was made. The limb was revascularised with guidewire directed aortic fenestration with angioplasty. TBAD was managed conservatively.We report a case of acute TBAD presented as isolated ALI, which was initially diagnosed and treated as an ALI unrelated to aortic dissection. TBAD with typical or atypical clinical features presented with ALI as a malperfusion syndrome is not uncommon. However, masquerade presentations of TBAD as ALI are rare in the literature. Endovascular fenestration with or without stenting has fewer neurological complications and long-term mortality than thoracic endovascular aortic repair (TEVAR). Moreover, they become convenient in resource-poor settings without dedicated aortic centres.Masquerade presentation of TBAD should be recognised in the differential diagnosis of ALI. Timely CTA would prevent unnecessary interventions and help diagnose TBAD complicated with ALI. Despite their availability, outcomes will depend on proper patient selection for endovascular, surgical, and TEVAR options.

In this paper daily confirmed cases of COVID -19 in different countries are modelled using different mathematical regression models. The mathematical curve fitting is used as a prediction tool to model both pervious and next upcoming Coronavirus waves. The used models cover virus spreading from 1/3/2020 to 10/4/2021. According to virus spreading, countries under study in this paper are categorized into three main categories. First category in which Coronavirus first wave takes about two year seasons (about 180 days) to make a complete virus cycle. Second category is countries with higher transmission rates with one year season (about 90 days) to make the first complete virus cycle. These countries take offline periods with low spreading rates. The third category is countries with the highest transmission rates and make complete virus cycles without offline periods. All categories are modelled with different mathematical fitting models. Finally, predictions of different upcoming scenarios for these countries are made. Funding Statement: The research is partially supported by P.R.I.N. 2019 and the RUDN University Program 5-100". Declaration of Interests: The authors have no competing interests.

This paper presents the design of a Three Stages Maximum Power Point Tracking (MPPT) charge controller for improving the charging/discharging control of the battery. In this research, Buck Converter is used to regulate the voltage from the Photovoltaic (PV) module to the required voltage. This research is limited to Valve Regulated Lead Acid (VRLA) battery for 12V system voltage. The charge control algorithm envisages controlling the charging and discharging action in all the three stages of battery charging, bulk, absorption, and float. The idea is to control the battery charging and discharging status until meeting the battery set-point. The set-point is limited to High Voltage Disconnect (HVD), Low Voltage Disconnect (LVD) and Load Voltage Reconnect (LVR) to protect the battery from over-charging and deep-discharging. The results obtained demonstrate the good performance of the charge controller. With the application of the MPPT algorithm in the bulk stage, the time taken to get the battery to fully charged state becomes faster The regulation power from the converter to the inverter has performed well and the switching relay is managed to be controlled.

Objectives. Assessing the therapeutic efficacy of superparamagnetic iron oxide nanoparticles (SPIO) labeled bone marrow-derived mesenchymal stem cells (BM-MSCs) on experimental liver fibrosis and associated dysplasia. Materials and Methods. MSCs were obtained from 10 male Sprague-Dawley rats while 50 female rats were divided into control (CG), liver fibrosis (CCL4, intraperitoneal injection of CCl4 for 8 weeks), and CCL4 rats treated with SPIO-labeled MSCs (MSCs/CCl4) with and without continuing CCL4 injection for another 8 weeks. Assessment included liver histopathology, liver function tests, transmission electron microscopic tracing for homing of SPIO-MSCs, immunofluorescence histochemistry for fibrosis and dysplasia markers (transforming growth factor-beta (TGF-β1), proliferation nuclear antigen (PCNA), glypican 3)), and quantitative gene expression analysis for matrix metalloproteinase-1 (MMP-1) and tissue inhibitor of metalloproteinase-1 (TIMP-1). Results. SPIO-labeled MSCs were engrafted in the fibrotic liver and the BM/MSCs demonstrated regression for fibrous tissue deposition and inhibition progression of dysplastic changes in the liver of CCl4-treated rats on both the histological and molecular levels. Conclusion. BM-MSCs possess regenerative and antidysplastic potentials.

This paper presents a power electronic devices application focus on modeling, analysis, and control of switching power converter in the inverting DC substation with regenerative braking system which is used to recycle the surplus regenerative power by feed it back to the main AC grid. The main objective of this research is to improve the switching power electronic converter of the railway inverting substation and optimize the maximum kinetic energy recovery together with minimum power losses from the railway braking system. Assess performance including efficiency and robustness will be evaluated in order to get the best solution for the design configuration. Research methodology included mathematical calculation, simulation, and detail analysis on modeling of switching power converter on inverting substation. The design stage separates to four main areas include rectification mode, regenerative mode, control inverter mode and filtering mode. The simulation result has shown that the regenerative inverter h...

This paper presents the current status of the grid-connected photovoltaic (GCPV) system installed in Malaysia. There are 113 sites with total PV capacity power, of 1008.73 kWp GCPV systems are monitored by the Photovoltaic Sys- tem Monitoring Centre (PVSMC). This paper focus on the PV system performances under Malaysian Building Integrated Photovoltaic (MBIPV) project which relates the performance of the system failures due to technical and environmental factors. Both factors will contribute to the reduction of the PV system performances in terms of final yield. It would later lead to energy inefficiency as the energy harvested from PV array will be wasted which later cause the time taken for en- ergy payback period of the system to be lengthen. Proper and sufficient practical knowledge in designing a GCPV system is needed in order to achieve maximum energy production. A database with minimum period of 4 years was selected as the benchmark for problem identification at PVs site in hot and humid climate. All issues affecting the system performances and BOS component of the GCPV system for optimization purpose.

Robustness of a battery management system (BMS) is a crucial issue especially in critical application such as medical or military. Failure of BMS will lead to more serious safety issues such as overheating, overcharging, over discharging, cell unbalance or even fire and explosion. BMS consists of plenty sensitive electronic components and connected directly to battery cell terminal. Consequently, BMS exposed to high voltage potential across the BMS terminal if a faulty cell occurs in a pack of Li-ion battery. Thus, many protection techniques have been proposed since last three decades to protect the BMS from fault such as open cell voltage fault, faulty cell, internal short circuit etc. This paper presents a review of a BMS focuses on the protection technique proposed by previous researcher. The comparison has been carried out based on circuit topology and fault detection technique

Solar Energy is one of the key solutions to future electrical power generation. Photovoltaic Plants (PV) are fast growing to satisfy electrical power demand. Different maximum power point tracking techniques (MPPT) are used to maximize PV systems generated power. In this paper, on grid PV system model in MATLAB SIMULINK is tested under sudden irradiance and cell temperature variations. Incremental Conductance MPPT is used to maximize generated power from the PV system with the help of new adaptive controller to withstand these heavy disturbances. The new adaptive controller is tuned for optimal operation using two different optimization techniques (Invasive weed and Harmony search).Optimization results for the two techniques are compared. .A robustness test is made to check system stability to withstand different random irradiance and cell temperature patterns without failure to track the maximum power point.Finally, a brief comparison is made with a previous literature and the new adaptive controller gives better results.

This paper examines the reactive power control capability of doubly fed induction generator connecting to distribution grid with and without the inclusion of capacitor banks. The dynamic response characteristics of the wind power generator in the case of fault in the network to assure the secure and reliable operation of wind farm is presented. The stator-flux- oriented vector control principle is applied to build a model of the doubly fed induction generator in dq synchronous coordination system and the simulation software is employed to investigate its performance into distribution grid of eleven nodes. Wind power may be considered one of the most promising renewable energy sources, but its integration into power systems has a number of technical challenges concerning security of supply, in terms of reliability, availability and power quality (1-3). Since penetration of wind power generation is growing, its impact on the connected power system must be analyzed. For this reason, grid connection requirements are established. In the last few years, the connection requirements have incorporated in addition to steady state problems, dynamic requirements, like voltage dip ride-through capability (4, 5). The most common requirements under these disturbances are low voltage ride through which usually implies: voltage profile immunity, reactive current injection, active and reactive power limitation under fault and recovery and limitation in reactive energy consumption (5, 6). In the past, before a serious failure in the electrical grid, energy conversion systems (WECS) were disconnected. However, due its penetration has been increased it is necessary that all time must remain connected, since they provide a large amount of power (7). The continuous operation under different perturbations is not easy to get, the control structure must ensure proper dynamic response. The major literature includes control structure to doubly fed induction generator (DFIG) connected to an infinite bus but does not contain all structure of the electrical grid (1, 8, 9). Analyzing a control scheme with a suitable model system largely ensure proper operation in actual conditions. Therefore, a comprehensive study of the electrical grid including WECS with detail control structure considering the effect of major disturbances and the behavior of voltage and power flows is required. cq cd r e cq r cq q c v i L dt di L Ri v     

Dual-power PV-grid system was introduced to manipulate the lower tariff rate at off-peak period and to reduce the capital installation cost of PV energy system. The power converter system consists of a boost regulator to boost and regulate PV outputs to fixed voltage of 240V, 50Hz, a maximum power point tracking (MPPT) to derive maximum power from PV panels and a three operation modes of the battery converter to regulate charging current/discharging current under various PV output and load variation. The system utilizes 25 levels of cascaded multilevel inverter to invert DC voltage from solar panel to AC voltage. The operation and the synchronization of the power converter system was digitally controlled to ensure the system works at maximum captured power, fast switching with minimum losses, and produces fixed 240 V, 50Hz power supply in variation of environmental conditions. In this paper, the control strategy implemented in the power converter system in the dual-power PV-grid energy system are described and discussed.

This paper focuses on a Grid-Connected Photovoltaic (GCPV) system of amorphous Silicon (a-Si) PV module technology with total PV capacity is about 1.179 kWp. This a-Si FS GCPV system is located near to the Green Energy Research Centre (GERC) Building at Universiti Teknologi MARA (UiTM) Shah Alam, Malaysia. This a-Si FS GCPV system installation was referred to Malaysian Standard MS1837:2010 and designed based on initial data values. These days, various of the GCPV system applications in Malaysia using thin-film PV module technology was designed at stabilised data values. So, this a-Si PV system is conducted to study the PV performances and behaviors under Malaysia's perspective. After the observation period, a-Si FS GCPV system performs in good condition. The PV system generated 644.40 kWh electrical energy during the first six months of operation (June-December 2011) and the average daily energy yield of 3.03 kWh. The average monthly final yield was found to be 78.0 kWh/kWp, while the range of the initial/stabilized performance ratios between 55.8% to 78.2% and 73.0% to 102.4%.

Dual-power PV-grid system was introduced to manipulate the lower tariff rate at off-peak period and to reduce the capital installation cost of PV energy system. In this paper, the system and simulation design of the system is discussed to evaluate the design parameters which affect the design performance of the power converter. It consists of a boost regulator to boost and regulate PV outputs to fixed voltage of 240V, 50Hz, a MPPT to derive maximum power from PV panels and a three operation modes of the battery converter to regulate charging current/discharging current under various PV output and load variation. The system utilizes 15 levels of cascaded multilevel inverter to invert DC voltage from solar panel to AC voltage. The simulation results certify the simulation model can emulate the real system.

This paper presents a modelling of Multiple Input-Single Output (MISO) model for tracking maximum point of Photovoltaic (PV) Systems. A system identification approach is used to obtain the model characteristics of existing structural systems through dynamic observations which incorporate with traditional direct control Maximum Power Point Tracking (MPPT) algorithm. The generate model characteristics was used in designing the MPPT of the Photovoltaic Systems. The need of an efficient mathematical model to characterize the dynamics system for PV is essential for implementing the system for control applications. In this paper, the transfer function relating the input parameters (Solar irradiance and cell temperature) and output parameter (DC current) of the PV module MF120EC3 was identify with the aid of MISO for Auto-Regressive with eXogenous input (ARX) model. The approach has concern on the estimation of the (Direct Current (DC) for photovoltaic system based on the real systems data from Pusat Tenaga Malaysia (Malaysia Energy Centre, MEC). A Fourth-order autoregressive (ARX) model using the ARX algorithm, (ARXQS) was chosen since the model output provide 93.42% best fit model criteria. The modelling is implemented using system identification toolbox of Matlab software.

This paper discussed the current status of a grid-connected photovoltaic (PV) system installed in Malaysia. There are 97 locations with capacity of array power, which is 857.92 kWp grid-connected PV systems are monitored by the Photovoltaic System Monitoring Centre (PVSMC), UiTM. Since monitoring the performances for grid-connected system, there are several sites had been detected facing problems involve technical problem like an inverter fault, sensor fault and environmental problem such as shading effect and lower energy. All the problem will be affected the PV system performances in terms of final yield and performance ratio thus it will be inclined the data availability problem. Furthermore, it could waste the energy produced by PV array and energy payback period. An established practical knowledge in designing a PV system need to be taken seriously in order to avoid improper design before installation to maximize the energy production. It is very important to structure proper design and sizing procedures, identify the factors which affect the performances and component sizing for PV system to optimize and utilize the energy production before any actual implementation of solar power energy system installed.

The present study was carried out to evaluate the potential protective role of quercetin and curcumin against paracetamol-induced oxidative injury, liver damage and impairment of kidney function, as well as haematotoxicity in rats. Also, N-acetylcysteine was used to evaluate the potency of quercetin and curcumin. Paracetamol caused an elevation in thiobarbituric acid-reactive substances (TBARS) paralleled with significant decline in glutathione peroxidase, glutathione S-transferase, superoxide dismutase and catalase activities (in plasma, brain, lung, heart, liver, kidney and testes) and glutathione content (in lung, liver and kidney). The apparent oxidative injury was associated with evident hepatic necrosis confirmed in histological examination, elevated plasma transmainases, alkaline phosphatase and lactate dehydrogenase. Paracetamol reduced plasma total protein, albumin and globulin, while increased bilirubin, urea and creatinine, and induced haematotoxicity. The presence of quercetin or curcumin with paracetamol successfully mitigated the rise in TBARS and restored the activities of antioxidant enzymes compared to the group treated with both paracetamol and N-acetylcysteine. They also protected liver histology, normalized liver and kidney functions, which was more pronounced with curcumin. Therefore, it can be concluded that concomitant administration of quercetin or curcumin with paracetamol may be useful in reversing the toxicity of the drug compared to N-acetylcysteine.

Ten years of climate and yield data were used to evaluate semi-mechanized rain-fed farming practices on vertisols in southern Somalia. Median rainfall totals for the main rainy season varied between 384 and 432 mm, and maize production was reasonably successful, with a rainfall water use efficiency for grain of 9 kg ha −1 mm −1 . Estimated probabilities of crop failure varied between 0.1 and 0.3, and of reasonable yields between 0.5 and 0.67. The local cowpea variety proved to have a low yield potential, with a water use efficiency of only 1 kg ha −1 mm −1 , but a low minimum water requirement, resulting in low yields but a low frequency of crop failure. Rainfall during the short rainy season was low and insufficient to justify cropping. Analysis of the relations of yield with current and preceding fallow rainfall indicated that fallow soil management failed to increase yields. Cumulative probabilities of planting rains did not reach 0.5 until the latter part of April which, together with the rapidly decreasing probabilities of rainfall during June, indicates that short-season maize varieties may be better adapted to the environment. The probabilities of too much rainfall hampering crop and soil management activities and causing crop waterlogging damage are sufficiently high to warrant investigations on methods of improved surface drainage.

This paper proposed a single-phase single-stage high DC voltage multiplier converter. The conversion of high DC voltage converter without a DC-link is involved. A high frequency transformer using ETD 59 ferrite core with ratio 1:1 is used as energy storage and also providing isolation. Cockcroft-Walton circuit is connected at secondary side of the transformer. AC input is controlled by IGBT switch which the current flow in both directions of the transformer to fully utilize the transformer core. The current flow is controlled by the IGBTs using PWM technique. Experimental and simulation results are provided to show the effectives of the proposed technique

A new method of controlling high DC voltage based on Cockcroft Walton voltage multiplier circuit by using digital controller is presented. The digital controller is developed using complex programmable logic devices (CPLD). The proposed system utilizes a single-phase AC as an input supply. The power switching devices in the controlled bridge are controlled by the multiple-pulse pulse width modulation (PWM) switching technique so as to minimize the low order harmonic present on the AC side of the converter system. A low pass filter is incorporated in the circuit to filter out unwanted harmonics and to give a sinusoidal AC current. A high frequency transformer with 1:1 ratio is incorporated in the design to provide galvanic isolation for better circuit performance and protection. The optimum operation of transformer core in four quadrant of B-H curve is also considered in the proposed converter topology. The laboratory model of the converter is developed and tested. The experimental result is compared with the simulation result.

A mathematical approach of modelling and analysing three-phase pulse width modulation (PWM) is presented. The three-phase flyback converter required a unique pattern of PWM to optimise the power transfer in the magnetic circuit used in the converter. The three-phase PWM is generated digitally based on uniform symmetrical sampling technique using Xilinx chip. The generated PWM pattern is able to reduce the magnitude of the low order of harmonic components present in the input AC supply. Although software simulation could simulate the PWM pattern, it does not represent the exact pattern as been generated digitally. The mathematical approach used is to model the PWM pattern exactly as been created digitally. The proposed mathematical technique could also be used to analyse any digital PWM. The result of the mathematical analysis on the PWM pattern could be used to study the characteristics of the pattern such as maximum and minimum value of duty cycle, pulse width, turn-on time, turn-off time and modulation index. To verify the validity of the proposed technique, the results obtained from the mathematical model, experimental and simulation using PSpice were compared

This paper describes the application of a new simple voltage-boosting feature to a split-supply SR (switched-reluctance) motor inverter. As its name implies, the SR motor always operates in switching mode and has distinct motoring and generating rotor angular regions. The effectiveness of the energy conversion process of the SR motor depends basically on the ability of its inverter to inject adequate current during the positive-torque angular region and to reduce the current to a negligible value during the negative-torque angular region. The modified inverter effectively generates boost voltages for accelerating current build-up and decay and hence enhances the performance of SR motor drives. Benefits of the added boosting include: higher average current; better energy recovery during commutation; and a wider feasible speed range. This paper assesses the implications of the boost feature on inverter cost and performance. A time-stepping simulation procedure which includes the modelling of current overlapping between phases is presented together with simulation results.

Iron, zirconium and copper samples were irradiated at 17.5 K by 10 to 16 MeV protons. The resistivity change was measured as a function of the bombarding dose. Values of the resistivity damage rate are determined from the experimental data and are compared with the corresponding estimates obtained from a modified Kinchin-Pease model and from a vacancy-recombination model. Good agreement is found between the latter model and the experimental results. The data are also compared with other proton irradiation and d-Be neutron experiments.

Stage I recovery is investigated for Fe, Zr and Cu irradiated at 17.5 K with 10,14 and 16 MeV protons. Several sub-stages are measured and analyzed. In relation to published electron and neutron irradiation data, the present results show that 16 MeV protons approximate the damage induced in metals due to fusion reactor spectra. The present results also indicate that the damage state created by protons in metals is similar to an intermediate state between those due to electron and fast-neutron irradiations.

Total scattering cross sections, the related recoil energy distributions, and damage energies are evaluated for 14 MeV neutrons and 10–20 MeV protons on Fe, Ni, Cu, Zr, Nb, and Au. The validity and limitations of using protons to simulate high energy neutron bombardment are discussed.

Iron and copper samples have been irradiated at 17K with 10–16 MeV protons to investigate the damage produced and, where possible, draw conclusions in relation to the use of such bombardments to simulate the damage resulting from the fusion neutron spectrum. The damage-dose behaviour and isochronal anneals appear to support the model of stimulated Frenkel-pair recombination in the vicinity of high energy density cascades.

The variation of lower yield stress with grain size has been established in niobium of two different levels of impurity. The results obey closely the Hall-Petch relationship, σy=σi + Kyd−12, with Ky⋍1.1 kg mm−32. The grain size dependence of the flow stress was found to obey a similar relationship, but with the parameter K < Ky, and increasing with strain. Niobium with ∼ 5 p.p.m. oxygen showed yield points after high temperature annealing, but was free from strain ageing effects in tensile tests above room temperature, and no recovery of yield phenomena was observed after ageing.

The design of a low temperature cryostat suitable for accelerator based radiation damage studies is presented. The system employs a commercial two-stage closed cycle helium gas cryorefrigerator and a mechanical heat switch to permit sample irradiations at 13–15 K and rapid temperatures cycling up to 300 K for post irradiation isochronal anneal studies. Al-In and Al-Ag switch contacts are evaluated for the cryostat.

This paper presents a theoretical analysis and practical implementation of the natural and regular (symmetric, asymmetric) sampled three-phase PWM waveform, which was digitally implemented on a microprocessor, and the essential considerations involved in the feasibility of using a microprocessor software-based calculation to generate PWM. All the necessary microprocessor hardware/software techniques and algorithms required to generate three-phase PWM are developed in detail, and demonstrated using practical results from an experimental microprocessor board. The techniques developed and presented in this paper are readily applicable to other currently available microprocessors, with minor modifications to reflect the special features of the particular microprocessor used. Particular emphasis has been placed on the basic concepts and principles, rather than concentrating on the details of a particular microprocessor.