Rotating Disk Apparatus: Types, Developments and Future Applications

Power consumption reduction investigations attracted the attention of enormous numbers of researchers in the past few decades due to its high academic and economic impacts. The pumping power losses during the transportation of crude oils are considered as one of the main power consuming applications due to the turbulent mode of transportation. Investigating the possible solutions for this problem is expensive and time consuming due to the large apparatuses needed to simulate the flow in real pipelines. Rotating disk apparatus (RDA) is an instrument mainly comprising a rotating disk and an electrical motor to rotate the disk, which was implemented as an efficient and economical path to simulate what can be done in pipelines through generating a controlled degree of turbulence. This technique was also used in many other scientific applications due to its dynamic mode of operation. For example, a rotating disk electrode was used in electrodeposition processes and to characterize deposition film thickness and uniformity. The rotating disk reactor was employed to investigate the reaction rate between fluids and solid surfaces. The present work evaluates the RDA from different prospective and applications in order to introduce it as an efficient research tools for future dynamic investigations

Active drag reduction in hydrocarbon media using rotating disk apparatus

A high precision rotating disk apparatus (RDA) is designed and employed to investigate the turbulent drag reduction characterization induced by polymeric additives. For the past few decades, polymers have been used widely as drag reducer agents in a pipeline and RDA successfully due to its viscoelastic properties that can suppress the turbulent at high ranges of Reynolds number. In this study, drag reduction efficacy of diesel fuel in a rotating disk apparatus is investigated using high molecular weight polyisobutylene polymer as drag reducing agent. Dependence of drag reduction on different parameters such as: polymer concentration and rotational disk speed (RPM) are also investigated. In addition, the mechanical stability of this polymer with time was studied by measuring torque values for 300 sec at a fixed rotational speed (2000 rpm). It was observed that the drag reduction of diesel fuel increases withthe rotational disk speed and polymer concentration till a critical concentration at which the maximum drag reduction achieved. The maximum DR obtained was about 19.197% at Re = 902062 and PIB concentration of 150 ppm

The application of predictive modelling for determining bio-environmental factors affecting the distribution of blackflies (Diptera: Simuliidae) in the Gilgel Gibe watershed in Southwest Ethiopia

Blackflies are important macroinvertebrate groups from a public health as well as ecological point of view. Determining the biological and environmental factors favouring or inhibiting the existence of blackflies could facilitate biomonitoring of rivers as well as control of disease vectors. The combined use of different predictive modelling techniques is known to improve identification of presence/absence and abundance of taxa in a given habitat. This approach enables better identification of the suitable habitat conditions or environmental constraints of a given taxon. Simuliidae larvae are important biological indicators as they are abundant in tropical aquatic ecosystems. Some of the blackfly groups are also important disease vectors in poor tropical countries. Our investigations aim to establish a combination of models able to identify the environmental factors and macroinvertebrate organisms that are favourable or inhibiting blackfly larvae existence in aquatic ecosystems. The models developed using macroinvertebrate predictors showed better performance than those based on environmental predictors. The identified environmental and macroinvertebrate parameters can be used to determine the distribution of blackflies, which in turn can help control river blindness in endemic tropical places. Through a combination of modelling techniques, a reliable method has been developed that explains environmental and biological relationships with the target organism, and, thus, can serve as a decision support tool for ecological management strategies

The impact of Stieltjes' work on continued fractions and orthogonal polynomials

Stieltjes' work on continued fractions and the orthogonal polynomials related to continued fraction expansions is summarized and an attempt is made to describe the influence of Stieltjes' ideas and work in research done after his death, with an emphasis on the theory of orthogonal polynomials

Vedic-Based Squarers with High Performance

Squaring operation represents a vital operation in various applications involving image processing, rectangular to polar coordinate conversion, and many other applications. For its importance, a novel design for a 6-bit squarer basing on the Vedic multiplier (VM) is offered in this work. The squarer design utilizes dedicated 3-bit squarer modules, a (3*3) VM, and an improved Brent-Kung Carry-Select Adder (IBK-CSLA) with the amended design of XOR gate to perform fast partial-products addition. The 6-bit squarer circuit can readily be expanded for larger sizes such as 12-bit and 24-bit numbers which are useful for squaring the mantissa part of  32-bit floating-point numbers. The paper also offers three architectures for 24- bit squarer using pipelining concept used in various stages. All these squaring circuits are designed in VHDL and implemented by Xilinx ISE13.2 and FPGA. The synthesis results reveal that the offered 6-bit, 12- bit, and 24- bit squarer circuits introduce eminent outcomes in terms of delay and area when utilizing IBK-CSLA with amended XOR gate. Also, it is found that the three architectures of 24- bit squarer present dissimilar delay and area, and the architecture design based on 3-bit squarer modules with  (3*3) VM introduces the lowest area and delay

Pattern of drug use in psoriasis inpatients in the department of dermatology at a tertiary care teaching hospital

Background: The pattern of drug use in people hospitalized with a primary diagnosis of psoriasis has never been studied previously in India. The aim of the study was to characterize the prescription pattern of people admitted to hospital with psoriasis so that rational prescribing could be promoted among dermatologists.Methods: Case files belonging to 32 patients, admitted in the Department of Dermatology with psoriasis, of a tertiary care teaching hospital in Kerala, over a period of 1-year were retrieved with the assistance of the medical records department. The data thus obtained was analyzed using descriptive statistics.Results: The average age of patients who were admitted with psoriasis was 49.9 years, and their average duration of hospital stay was 7.96 days. A total of 296 formulations were prescribed to 32 patients. Out of 296 formulations, only 10 (3.37%) were generic and rest 286 (96.62%) branded. Fixed dose combinations consisted of 32.43% (96/296) of the prescribed formulations. Psoriasis vulgaris (56.25%) was the most common cause for admission. Of all the prescribed medications, 4 (1.35%) did not contain clear instructions for the route of administration. Strength was clearly mentioned in only 89 (30%) of the preparations. In 98% of the prescriptions, the exact dose was missing.Conclusions: The study reveals various deficiencies which exist in the prescribing pattern of drugs for management of psoriasis. Educational interventions among the doctors as well as students should be carried out to promote rational drug use.

Power management and control strategies for off-grid hybrid power systems with renewable energies and storage

This document is the Accepted Manuscript of the following article: Belkacem Belabbas, Tayeb Allaoui, Mohamed Tadjine, and Mouloud Denai, 'Power management and control strategies for off-grid hybrid power systems with renewable energies and storage', Energy Systems, September 2017. Under embargo. Embargo end date: 19 September 2018. The final publication is available at Springer via https://doi.org/10.1007/s12667-017-0251-y.This paper presents a simulation study of standalone hybrid Distributed Generation Systems (DGS) with Battery Energy Storage System (BESS). The DGS consists of Photovoltaic (PV) panels as Renewable Power Source (RPS), a Diesel Generator (DG) for power buck-up and a BESS to accommodate the surplus of energy, which may be employed in times of poor PV generation. While off-grid DGS represent an efficient and cost-effective energy supply solution particularly to rural and remote areas, fluctuations in voltage and frequency due to load variations, weather conditions (temperature, irradiation) and transmission line short-circuits are major challenges. The paper suggests a hierarchical Power Management (PM) and controller structure to improve the reliability and efficiency of the hybrid DGS. The first layer of the overall control scheme includes a Fuzzy Logic Controller (FLC) to adjust the voltage and frequency at the Point of Common Coupling (PCC) and a Clamping Bridge Circuit (CBC) which regulates the DC bus voltage. A maximum power point tracking (MPPT) controller based on FLC is designed to extract the optimum power from the PV. The second control layer coordinates among PV, DG and BESS to ensure reliable and efficient power supply to the load. MATLAB Simulink is used to implement the overall model of the off-grid DGS and to test the performance of the proposed control scheme which is evaluated in a series of simulations scenarios. The results demonstrated the good performance of the proposed control scheme and effective coordination between the DGS for all the simulation scenarios considered.Peer reviewedFinal Accepted Versio

Effect of Urea Fertilizer Deep Placement Days after Transplanting Using BRRI Prilled Urea Applicator on Transplanted Boro Rice Yield

Rice is the most important crop in the developing countries of Asia. In the south and south-east Asia, rain-fed and irrigated transplanted rice occupies nearly two-thirds of the rice-growing area and produces more than 80% of the rough rice. In these areas, prilled urea conventionally applied by farmers is very insufficient in the transplanted rice field, where severe losses occur (up to 60% of applied N) via NH3volatilization, denitrification, leaching, and runoff. Considering loss minimization, an experiment was conducted during the Boro season at Bangladesh Agricultural Development Corporation (BADC) in Sylhet to evaluate the performance of BRRI Prilled Urea Applicator (BPUA) at the different periods after transplanting BRRI dhan28. The results reveal that the field performance of the BPUA was suitable on first day after seedling transplanting under sandy clay loam soil compared to the third day after transplanting (DAT). At the 105 DAT, the height of the crop was found to be 104.3, 104.3, and 95.7 cm for urea deep placement by BPUA on first, second, and third day after seedling transplanting respectively. The maximum grain and straw yield was found at 6.8 t ha-1 and 5.2 t ha-1, respectively which varied with the date of applicator operation after seedling transplanting. The benefit-cost ratio was found 1.63 at first DAT, whereas it was lower on the third days after seedling transplanting. Farmer can apply urea fertilizer in the non-oxidized zone by the BPUA after the first and second day of seedling transplanting in the sandy clay loam soil for maximum yield