AC voltage regulation of a bidirectional high-frequency link converter using a deadbeat controller

This paper presents a digital controller for AC voltage regulation of a bidirectional high-frequency link (BHFL) inverter using Deadbeat control. The proposed controller consists of inner current loop, outer voltage loop and a feed-forward controller, which imposes a gain scheduling effect according to the reference signal to compensate the steady-state error of the system. The main property of the proposed controller is that the current- and the voltage-loop controllers have the same structure, and use the same sampling period. This simplifies the design and implementation processes. To improve the overall performance of the system, additional disturbance decoupling networks are employed. This takes into account the model discretization effect. Therefore, accurate disturbance decoupling can be achieved, and the system robustness towards load variations is increased. To avoid transformer saturation due to low frequency voltage envelopes, an equalized pulse width modulation (PWM) technique has been introduced. The proposed controller has been realized using the DS1104 digital signal processor (DSP) from dSPACE. Its performances have been tested on a one kVA prototype inverter. Experimental results showed that the proposed controller has very fast dynamic and good steady-state responses even under highly nonlinear loads

Effects of Metolachlor, Oxyfluorfen and Picloram on Cellulose Decomposition in a Peat Soil under Laboratory Conditions

The effects of the three herbicides, metolachlor, picloram and oxyfluorfen on cellulose decomposition were studied in a peat soil in laboratory experiments. The herbicides were either sprayed on to cellulose substrate before burial or incorporated directly into the soil. The herbicides applied directly to the substrates before burial reduced the decomposition of the substrate more than those applied to the soil. Pre-incubation of the treated soil for 4 weeks before burial slightly increased the decomposition rate after 6 or 12 weeks of incubation

PREVALENCE OF ACADEMIC STRESS AMONG MEDICAL AND PHARMACEUTICAL STUDENTS

Prevalence of academic stress among university students has been high across the world. Most studies on such topic have been conducted in limited population, particularly in the students of medical faculty and the publicly secular-based university. The present study was carried out on students at the department of medicine and department of pharmacy, the Universitas Islam Negeri (UIN) Maulana Malik Ibrahim Malang, Indonesia. This study was aimed to describe the level of academic stress prevalence among the students as well as its difference based on demographics, including department, gender, and previous education backgrounds. This study involved 72 students as participants. The results indicated that the prevalence of academic stress reached 61% in the medical students and 48.4% in the pharmaceutical students. Meanwhile, there were no significant differences in the level of prevalence in terms of department, gender, and educational background (P > .05). Academic stress was experienced by the students of various departments, from the differing previous education background, i.e., the Public Senior High School (Sekolah Menengah Atas), Islamic Senior High School (Madrasah Aliyah), and Islamic Boarding School (Pesantren), both the males and females. A high prevalence of academic stress among students at the Islamic university should draw more attention and call for special intervention from the unit of guidance and counseling service.  Article visualizations

Natural fiber for green technology in automotive industry: a brief review

Fiber reinforced polymeric composites have been known and widely used because of their high specific strength and modulus compared to metals. In the last few years, biomaterials listed as a demand technology to be exploring by researchers especially in industrial purpose. This is push by environmental awareness and the over use of petrol resources lead to the development of new materials, called biocomposites, which will maintain a better future. This paper will be discussing about a brief review of natural fibers, use in automotive industry to achieve a green technology target in manufacturing of cars specifically. It's a fact that, related to weight reduction, the automotive industry can take advantages of using these materials, not only because of extinction of oil reserve, but because of high ability and importance of these materials itself in automobiles. Currently, most composites in the market are focused with long-term durability design while using nondegradable polymeric resins such as epoxies and high-strength fiber such as glass. All these materials prove to be a good characteristic of composite but still lack in environmental concern. This polymer and fiber are derived from petroleum, a nonreplenishable commodity. The momentum is to use biocomposites in common plastics to improve performance. Since the main purpose of this paper is to show a bio-composite which is suitable to replace the existing interior of automotive design, the work has focused on obtaining that bio-composite, taking account into the raw-materials cost reduction and the maintenance of the manufacturing process based on current scenario. The automotive industry is in their way to expand green technology in composites because the need is greatest. But producing the composites is energy intensive and polluting, while the durability of conventional composites, often seen as an advantage, is also their biggest challenge. Current fibers use in industry right now is difficult to dispose. They do not degrade naturally and could linger for generations

Partnership Program Evaluations Shelled Crab Cultivation of a Triangle Pattern in the Post and Marine Fisheries Extension Services in Sub Tangkahan Durian Western Districts Berandan Langkat District of North Sumatra Province

The research was conducted on 27 March to 3 April 2015 in the Village of West Berandan Tangkahan Durian Langkat District of North Sumatra province. The research goal is to investagate increase in business scale and increase revenues before and after the program. Of the various indicators of business as the implementation of business partnership program soft shelled crab cultivation triangle pattern has increased the scale of business of 252.5 kg/person/year, increase the production of 466 kg/person/year, and grow profits for beneficiaries an average of 22.168.500/ person/year. Business partnership program soft shelled crab cultivation triangle pattern has given the average rate of profit to the owners of capital of 0.54% per year or 4.5% per month and this has far exceeded the interest rates on deposits offered by banks, which only reached 7 to 12% per year. Controllers aspect of the program also provides a profit of Rp. 66.97431 million or 58.2% per year and has opened up jobs for two people with a minimum salary of each of Rp. 2,000,000 per month.Of the various aspects that have been evaluated, we conclude that the business partnership program soft shelled crab cultivation triangle pattern appropriate to proceed and the business opportunities that provide benefits to both the beneficiaries, the owners of capital and controllers

Hubungan Amalan Pergudangan Dengan Prestasi Organisasi Pergudangan : Pengenalan Kepada Kerangka Konsep

Pengurus pergudangan meletakkan harapan besar ke atas amalan-amalan yang diamalkan supaya ia dapat menghasilkan prestasi organisasi yang membanggakan. Kajian mengenai amalan pergudangan dan hubungannya dengan prestasi organisasi kurang diberikan tumpuan padahal permintaan ke atas sektor pergudangan adalah kedua tertinggi selepas pengangkutan dalam industri 3PLs. Oleh itu, kerangka konsep yang diperkenalkan ini sedikit sebanyak dapat membantu memperbanyakkan kajian dalam sektor pergudangan.Dengan menjadikan teori RBV sebagai asas untuk kepada pembangunan kerangka konsep mengenai hubungan amalan pergudangan dengan prestasi organisasi pergudangan amat bertepatan sekali kerana teori tersebut menyokong konsep hubungan sumber-sumber organisasi dengan prestasi. Sumber-sumber organisasi seperti sumber manusia, teknologi maklumat, material pengendalian dan jaringan telah dicadangkan dalam kerangka konsep untuk diuji bagi melihat hubungannya dengan prestasi organisasi. Kerangka konsep ini amat sesuai untuk diuji ke atas syarikat yang menjadikan perkhidmatan pergudangan sebagai teras perniagaan mereka.disebabkan survival perniagaan syarikat ini amat bergantung kepada amalan dan prestasi