Simulasi dan Deteksi Gangguan Belitan Stator Motor Induksi Tiga Fasa Menggunakan Arus Starting dengan Matlab/Simulink

Induction motors are electric motors are the most widely used in industry, therefore the performance, stability and efficiency of an induction motor is of considerable concern to anticipate disturbances that could lead to a decrease in the age of the induction motor. Motor Current Signature Analysis (MCSA) is one of the most common method used to detect the motor's performance on-line, but the use of this MCSA not give less good results when the load torque is not constant. Modeling the induction motor in a state of no interference derived from mathematical equations with the method of the reference frame stator (stationary reference frame). In this paper, interference with the stator winding is detected by a change in resistance and inductance then and the emergence of sideband frequencies / other at the starting stator current spectrum, then do the phase characteristic approach todiagnosis techniques Fast Fourier Transform (FFT). Analytical results from the use of such techniques show an increase the amount of energy in each frequency band and a large rangeTHD each interruption, so that the motor condition can be known whether normal or damage occurs.Keywords - induction motor, the stator windings, short circuit, Fast Fourier Transform, software matla

Pengaruh Pola Penggunaan Otomotif Angkutan Umum Perkotaan terhadap Hilangnya Kapasitas Baterai Berbahan Lead Acid secara Prematur

– Baterai berbahan Lead Acid (BLA) digunakan pada hampir semua kendaraan termasuk angkutan umum beroda empat. Kecepatan penuaan pada proses penuan BLA sangat dipengaruhi oleh cara penggunaan BLA. Pengisian yang berlebihan, akan mengakibatkan korosi dan mempercepat penguapan air. Bertambahannya siklus pembebanan dalam (depth of discharge), degradasi massa postifif akan terakselerasi. Beberapa kerusakan Selain itu pembebanan yang berlebihan juga akan mengakibatkan lepasnya masa positif dari grid karena proses pembebanan BLA yang melebihi seharusnya. Keawetan BLA pada Angkutan umum perkotaan sangat ditentukan pola penggunaannya. Karakteristik operasional yang sering menuntut kendaraan berhenti akan memiliki pengaruh jenis kerusakan tertentu pada komponen BLA Penelitian ini akan mengeksplorasi karakterristikoperasional angkutan perkotaan. Dengan diketahuinya karakteristik operasionalnya maka dapat disiapkan langkah antisipatif dan prediktif dalam hal perawatan dan penggunaan BLA sehingga masa servis BLA akan lebih panjang serta meningkatkan efisiensi biaya para pemilik angkutan perkotaan. Keywords – BLA (Lead Acid Battery), transportasi perkotaan, masa servis BL

Counterion Condensation on Spheres in the Salt-free Limit

A highly-charged spherical colloid in a salt-free environment exerts such a powerful attraction on its counterions that a certain fraction condenses onto the surface of a particle. The degree of condensation depends on the curvature of the surface. So, for instance, condensation is triggered on a highly-charged sphere only if the radius exceeds a certain critical radius \collrad^{*}. \collrad^{*} is expected to be a simple function of the volume fraction of particles. To test these predictions, we prepare spherical particles which contain a covalently-bound ionic liquid, which is engineered to dissociate efficiently in a low-dielectric medium. By varying the proportion of ionic liquid to monomer we synthesise nonpolar dispersions of highly-charged spheres which contain essentially no free co-ions. The only ions in the system are counterions generated by the dissociation of surface-bound groups. We study the electrophoretic mobility of this salt-free system as a function of the colloid volume fraction, the particle radius, and the bare charge density and find evidence for extensive counterion condensation. At low electric fields, we observe excellent agreement with Poisson-Boltzmann predictions for counterion condensation on spheres. At high electric fields however, where ion advection is dominant, the electrophoretic mobility is enhanced significantly which we attribute to hydrodynamic stripping of the condensed layer of counterions from the surface of the particle.Comment: 13 pages, 9 figures and two table

Activation of endothelial cells and its potential involvement in blood-brain barrier damage in cerebral malaria: an in vitro study

Cerebral Malaria (CM), a severe complication in Plasmodium falciparum infection is classified as one of the main causes of mortality in malaria. The clinical outcome of CM, broadly varies from recovery to a lethal endpoint. Investigation of post-mortem brain tissue of CM patients demonstrates BBB breakdown (microhaemorrhages) with loss of tight junction proteins (TJPs), occludin, claudin-5 and ZO-1 in endothelial cells. Interestingly, this was observed in vessels in the presence and in the absence of sequestered PRBC. This suggested the mobilisation of direct and indirect mechanisms following PRBC sequestration. In previous studies, the endothelial cell monolayer integrity was reduced when cocultured directly with PRBC. To investigate the indirect effect of sequestration to the BBB integrity, human brain endothelial cells (tHBEC) were first co-cultured with PRBC after which, the co-culture supernatant was harvested and analysed for the presence of candidate soluble factors and functional assays performed. Interestingly, analysis of the co-culture supernatant showed the induction of the ADAMTS family of protease, ADAMTS-4. In addition, differential regulation of ADAMTS-1 and the matrix metalloproteases (MMP) family proteases, MMP-2 and MMP-9 was observed. Treatment of freshly cultured tHBEC monolayer with the co-culture supernatant demonstrated up to 2-fold reduction in tHBEC monolayer integrity within 3 hours, measured using FITC-dextran permeability assay. This was accompanied by reduction in the TEER and the endothelial cell TJPs. We propose that endothelial cell derived proteases in the co-culture supernatants that are released as a result of interaction with PRBC, during sequestration; contribute to BBB breakdown in CM

Fracture properties of reclaimed asphalt pavement mixtures with rejuvenator

Reclaimed asphalt pavement (RAP) technology has been extensively promoted to conserve depleting virgin materials for asphalt mixtures. High RAP content is desirable from economic and environmental standpoints. However, RAP mixtures become too stiff and require modification such as rejuvenator. This paper presents the evaluation on the fracture characteristics of mixtures prepared with 50% and 70% RAP, with and without rejuvenator that were subjected to indirect tensile strength (ITS) and notched semi-circular bending (SCB) tests. The fractured surfaces of the tested specimens were quantified using geospatial imaging technique to identify the proportion contribution to failure, namely cohesive, adhesive and broken aggregates. The results showed that the fractured rejuvenated mixtures were predominantly of the cohesive type when compared with the non-rejuvenated mixtures. On the other hand, the failure modes of non-rejuvenated mixtures were of the adhesive and aggregate failure types. The measured ITS at two temperatures corresponded with the expected damage trends. Similar behaviour was found in the derived fracture energy and pre-peak slope that were obtained from the SCB pure tensile and tensile-shear load–displacement curves. The findings showed that the fracture properties of rejuvenated mixtures performed comparably with virgin mixtures in terms of fracture toughness, tensile strength and proportion of damage contribution

Karakteristik Briket Arang Serpihan Kayu dengan Penambahan Arang Tempurung Biji Karet

The purpose of this study was to determine the characteristics of charcoal briqutte charcoal mixture of wood chips with charcoal rubber seed No- quality according to SNI 01-6235-2000. Research using completely randomized design (CRD) with charcoal treatment comparison wood chips and coconut shell charcoal rubber seed (K0 = 100%: 0%); (K1 = 90%: 10%); (K2 = 80%: 20%); (K3 = 70%: 30%); (K4 = 60%: 40%); (K5 = 50%: 50%). The results showed that variations in mix charcoal wood chips and coconut shell charcoal rubber seeds significantly affect the density,press charcoal briquettes, moisture content, levels of substance evaporates, ash content, bound carbon content and calorific value briquettes. The result showed that the best treatment in treatment K5 namely charcoal briquettes are made with 50% charcoal wood chips and 50% charcoal rubber seed with higher levels of density 0,901 g/cm3, firmness press of 0,466 kg/cm2, the water content of 2,86%, levels of substance evaporates 36,04%, ash content 5,11%, bound carbon content 58,84%, calorific value of 5492,438 cal/g

Penerapan Pendekatan Contextual Teaching And Learning (CTL) pada Materi Larutan Penyangga Kelas XI IPA 1 SMA Negeri 1 Poso Pesisir Utara

The use of learning approach applied to the study of chemistry is still one-way, the student just as a listener and not actively involved in the learning process. This research aims to determine the learning outcomes to the students who take buffer to the grade XI IPA I SMAN 1 Poso Pesisir Utara with contextual teaching and learning approach was better than the grade that follows the learning without contextual teaching and learning approach. The research population was all students of class XI IPA I SMAN 1 Poso Pesisir Utara in academic year 2013-2014 amounted to 65 studets were distributed in to classes. The research sample was determined by purposive sampling, 33 class XI IPA I as the experimental class and 32 class XI IPA 2 as control class. The data collection using test instruments in the form of 18 multiple-choice items that had been tested for validity and reliability. chemistry achievement of buffer test material, research data testing use t-test statistical p-analysis of the parties to the prerequisite test, test for normality and homogeneity tests. The analysis statistical hypothesis t-test was obtained value of tcalculate = 2.41 and ttable value = 1.67 this implies rejection of Ho. It can be concluded that the approach contextual teaching and learning effect on learning outcomes of students of the grade XI IPA I at SMAN 1 Poso Pesisir Utara in the material buffer with a good score than the conventional learning

Cyberterrorism: A Comparative Legal Perspective

The paper focuses on cyberterrorism and a comparative legal perspective with a view to examine the cyberterrorism as a concept as well as its definition. The revolution of development of Information and Communication Technology (ICT) has changed society to be a point where advances in programming computer and intelligence software operates in a higher processing capacity. The uses of desktop or laptops computers are leading the society to a time where or when cyber used to perpetrate various act of offences. The paper analyses legal perspective that introduced the Cybercrime Convention in Europe in relation to cyber terrorism and the opening to other Member States, while Economic Community for West African States (ECOWAS) issues a Directive to Member States to adopt enabling laws so as to combat the practices of cybercrime in relation to cyber terrorism. The paper argues that Nigerian Cybercrime Act 2013 is an established law that addresses the endemic practice of cybercrime and provides for cyber terrorism. Further, the paper examines the Nigerian financial regulators like the Central Bank of Nigeria (CBN), the Economic Financial Crimes Commission (EFCC) and other Units mandated to curb the money laundering and combating the financing terrorism and other financial institutions related crimes. The paper relies on primary and secondary sources of data and the analysis is descriptive in nature. The paper will proffer recommendations and conclusions for effective measures for proper implementation and enforcement. Keywords: Cyberterrorism, definition of cyberterrorism, Relevance of cyberterrorism in cyberspace, Comparative Legal Perspectiv