An enhanced control strategy based imaginary swapping instant for induction motor drives

<p>The main aim of this paper is to present a novel control approach of an induction machine (IM) using an improved space vector modulation based direct torque control (SVM-DTC) on the basis of imaginary swapping instant technique. The improved control strategy is presented to surmount the drawbacks of the classical direct torque control (DTC) and to enhance the dynamic performance of the induction motor. This method requires neither angle identification nor sector determination; the imaginary swapping instant vector is used to fix the effective period in which the power is transferred to the IM. Both the classical DTC method and the suggested adaptive DTC techniques have been carried out in MATLAB/SimulinkTM. Simulation results shows the effectiveness of the enhanced control strategy and demonstrate that torque and flux ripples are massively diminished compared to the conventional DTC (CDTC) which gives a better performance. Finally, the system will also be tested for its robustness against variations in the IM parameters.</p>

Mathematical Models for Asymmetric Warfare

Differential equations developed by William Lanchester for combat models are still used by military theorists in traditional and asymmetric wars. The paper focuses on the asymmetric situation encountered in narrow exits on the battlefield, where it is impossible to concentrate the entire firepower. Based on the application of the Lancaster Equation, it is determined that in order to achieve parity, it is necessary to destroy targets by sequentially massaging fire. The mathematical model proposed for the destruction of forces by divisions even allows to determine how to divide the opposing forces into the optimal number for each battle. Based on the research, the influence of the time factor on the element of surprise is determined and a mathematical model is developed, which can determine the effective period of fighting the opponent.

New Online Shunt Acidification for Water Injection Increasing Technology and Its Application in Huanjiang Oilfield

The poor physical property and strong heterogeneity of Triassic Yanchang formation in Huanjiang oilfield of Ordos Basin are the main reasons for uneven water absorption, partial injection wells underinjection at high pressure, and decline of production. Previously, large numbers of conventional acidifications were used for plugging removal in the reservoir, but the effect was not so good and effective period was short. Aiming at the geological characteristics of Huanjiang oilfield, an online shunt acidification and augmented injection technology which does not stop water injection, pull original production strings out, and continuously inject acid and diverting agent has been proposed. A chelating acid COA-1S with low corrosion rate (0.3675 g/(m2·h)), good retardation capacity (hydrolysis constant = 1.2 × 10−6), and effective chelating ability (precipitation inhibition rate >95%) has been developed, as well as a diverting agent COA-1P with good dispersion in acid solution, diversion effect, and particle size (10–100 μm), which behaves well in COA-1S acid. It has been proved that the online acid system has a good diversion acidizing ability and plugging removal performance in a deep area in the laboratory core physical simulation test. The field test results show that the online shunt acidizing and augmented injection technology could reduce the injection pressure significantly (4.2 MPa) and increase water injection by 10 m3/d for the measured well (H5) and improve the water injection profile prominently. The online shunting acidification and augmented injection technology have the following advantages: simple procedures, fewer equipment needed, high efficiency of depressurization, and increasing water injection, which could effectively improve the profile of water wells, and there is a bright future of the technology.

Impact of Storage Conditions on Shear Strength of Beech (Fagus sylvatica L.) and Sessile Oak (Quercus petraea (Matt.) Liebl.)

The structure of a bark as a component of a living tree is completely different from wood. Different structures significantly influence the physical and mechanical properties of the bark. In the processing of logs, it is in most cases necessary to separate the bark from the wood. Problems can arise mainly in the pulp and paper industry. The research focused on the impact of storage conditions on shear strength, showing that the value of shear strength decreased remarkably due to the storage. A decrease in strength can mainly be explained by the changes in the moisture content of bark, remarkably affected by the surrounding environment (climate). The research showed that three months of storage seemed to be the most appropriate and effective period for removing the bark in the case of beech logs and that a storage time of up to five months was the best in the case of oak logs.

Asymmetric Diffraction in Plasmonic Meta-Gratings Using an IT-Shaped Nanoslit Array

Diffraction is a fundamental phenomenon that reveals the wave nature of light. When a plane wave is transmitted or reflected from a grating or other periodic structures, diffracted light waves propagate at several angles that are specified by the period of the given structure. When the optical period is shorter than the wavelength, constructive interference of diffracted light rays from the subwavelength-scale grating forms a uniform plane wave. Many studies have shown that through the appropriate design of meta-atom geometry, metasurfaces can be used to control light properties. However, most semitransparent metasurfaces are designed to perform symmetric operation with regard to diffraction, meaning that light diffraction occurs identically for front- and back-side illumination. We propose a simple single-layer plasmonic metasurface that achieves asymmetric diffraction by optimizing the transmission phase from two types of nanoslits with I- and T-shaped structures. As the proposed structure is designed to have a different effective period for each observation side, it is either diffractive or nondiffractive depending on the direction of observation. The designed structure exhibits a diffraction angle of 54°, which can be further tuned by applying different period conditions. We expect the proposed asymmetric diffraction meta-grating to have great potential for the miniaturized optical diffraction control systems in the infrared band and compact optical diffraction filters for integrated optics.

Econometric modelling of bank activities: value-based approach to the problem loans terms’ rescheduling

The permanent state of the financial crisis has predictably brought to the forefront such traditional problem of banking as problem loans. This research aims to work out an econometric approach to the solution of the problem of loans terms’ rescheduling. For this purpose, we, firstly, treated credit as a bank’s investment project with cashflows’ chart including initial outflow (principal) and following inflows represented by loan payments. Secondly, we combined the schematic representation of loan’s cashflows with NPV formula accustomed to loan’s cashflows and it allowed to create the econometric models for three types of loan: classic, annuity, serial. Thirdly, for the case when borrower breaks a loan’s payment schedule and it leads to the reduction of loan’s NPV and loss of the wealth of bank’s shareholders, respectively, we outlined special compensative models of cashflows where default in payment is interpreted by the lender as an additional forced loan. We suggested modifying the loan terms (interest rate or effective period of the loan agreement) for the rest of payment periods. Fourthly, we laid the special compensative models of forced loans’ cashflows a top corresponded initial cashflows of loans and this has made it possible to get formulas calculating the modified interest rate and the additional number of loans’ payment periods with the aid of backward calculation. As a result, we developed the econometric models of the loan terms’ modifications based on the prolongation of the initial credit period and the increasing of the initial interest rate.

Effectiveness of Cymbopogon citratus Oil Encapsulated in Chitosan on Colletotrichum gloeosporioides Isolated from Capsicum annuum

One of the principal etiological agents associated with losses in horticultural crops is the fungus Colletotrichum sp. This study aimed to evaluate the in vitro effectiveness of the essential oil (EO) from Cymbopogon citratus in chitosan supports for the control of Colletotrichum gloeosporioides isolated from sweet pepper plants. Methods: The extraction and phytochemical analysis of the EO of C. citratus were performed along with its encapsulation in chitosan-agar in order to compare it with other techniques and determine its effect on C. gloeosporioides. Results: The EO from the citral chemotype (58%) encapsulated in the chitosan-agar, with an 83% encapsulation efficiency in mass percentage, resulted in the total inhibition of mycelial growth at a minimum inhibitory concentration of 1370 ppm. This concentration was effective in controlling the disease under greenhouse conditions. The effectivity of the capsules containing EO was superior to that of other controls using EO evaluated in vitro. The capsules demonstrated an effective period of 51 days, with an additional 30 days of effectiveness after a reinfection cycle, thus providing similar results to the control with Trichoderma sp. Conclusions: Chitosan capsules present a promising strategy in the use of C. citratus EO on C. gloeosporioides, and they are highly effective and stable under in vitro and field conditions

POTENSI USAHA MASYARAKAT DESA KEDONDONG DI HTI HUTAN KETAPANG INDUSTRI KABUPATEN KETAPANG

The purpose of this study was to obtain information business potentials for local community in Kedondong village that could develop with the establishment of PT Hutan Ketapang Industri. Analyze the potential of local resources and the economic impact of the bussines potensial at Kedondong village take by direct interviews to respodent. This research was conducted in Kedondong Village, Kendawangan District, Ketapang Regency with an effective period of 4 weeks in the field. Equipment used in this study included a list of questions, stationery, cameras and voice recorders. Data collection is done using survey methods and direct observation in the field. Sampling was done by Slovin technique. Based on the results of the study, local community efforts to business potential in Kedondong Village with establisment PT HKI, which is done by the community including utilizing vacant land to be used as agricultural land, gardens, livestock or, among others, opening business opportunities such as food stalls, workshops, agriculture and fishery.Keywords: Business Potential, Kedondong village, PT HKI

Antioxidative Potential of Red Deer Embryos Depends on Reproductive Stage of Hind as a Oocyte Donor

The aim was to compare the blastocyst stages of red deer embryos in respect of in vitro fertilization (IVF) efficiency, morphology, apoptotic and proliferative abilities, and antioxidative potential according to the reproductive status of hinds. We used three experimental groups, including the ovaries collected post mortem on the 4th and 13th days of the estrous cycle and during pregnancy (n = 18). After oocyte maturation, frozen-thawed epididymal semen was used for IVF. Blastocyst quality, apoptotic potential by determining the mRNA expression of BAX, BCL-2, OCT4, SOX2, and placenta-specific 8 gene (PLAC8), and antioxidative potential of blastocysts were evaluated by determining the mRNA expression of CuSOD, MnSOD, and GPX as well as the enzymatic activity of superoxide dismutase and reduced glutathione. The highest development rate of expanded blastocyst, mRNA expression of BCL-2, OCT4, SOX2, and PLAC8 and mRNA expression and enzymatic activity of the antioxidative factors increased (p < 0.05) in blastocysts developed from the oocytes collected on the 4th day, compared to those developed from the oocytes collected on the 13th day of the cycle and during pregnancy. Our study indicates that the 4th day of the estrous cycle is the most effective period for oocyte collection for IVF and embryo development in hinds, considering quality parameters and antioxidative potential of the blastocysts.

Five years Retrospective Study of Avian Coccidiosis in a Veterinary Clinic Bukuru Plateau State Nigeria

This study was conducted to evaluate the incidence of coccidiosis and its association with various risk factors such as age, type of birds and season in a private veterinary clinic in Bukuru, Plateau State Ngeria. A total of 9406 cases during 2013 – 2017 were analysed and 1556 of them were positive for coccidiosis. Several reports on the prevalence of avian coccidiosis have been documented; however, in this study the prevalence of coccidiosis in the study area and its economic consequences was enumerated. Total prevalence of 12.14% in 2013, 18.78% in 2014, 18.21% in 2015, 16.82% in 2016 and 19.07% in 2017 were reported. An overall prevalence of 85.02% was recorded. The average prevalence of coccidiosis based on this five years study is 17%. The association between coccidiosis and age of the birds was determined and age 5-8 weeks becomes most effective period with wet season having high percentage prevalence of coccidiosis. Based on the type of birds, coccidiosis is prevalence almost in equal proportion in both broilers and layers. The losses associated with coccidiosis both direct and indirect components include the cost of control measures, inadequate good hygiene practices, production losses and lack of prophylaxis treatment. The control of coccidiosis is by good sanitary measures by avoiding water spillage, overcrowding, the use of prophylaxis anticoccidials and proper vaccination.