PFC Topologies for AC to DC Converters in DC Micro-Grid

With increasing dominance of renewable energy resources and DC household appliances, the novelty of DC micro grid is attracting significant attention. The key interface between the main supply grid and DC micro grid is AC to DC converter. The conventional AC to DC converter with large output capacitor introduces undesirable power quality problems in the main supply current. It reduces system efficiency due to low power factor and high harmonic distortion. Power Factor Correction (PFC) circuits are used to make supply currents sinusoidal and in-phase with supply voltages. This paper presents different PFC topologies for single phase AC to DC converters which are analyzed for power factor (PF), total harmonic distortion (THD) and system efficiency by varying output power. Two-quadrant shunt active filter topology attains a power factor of 0.999, 3.03% THD and 98% system efficiency. Output voltage regulation of the presented active PFC topologies is simulated by applying a step load. Two-quadrant shunt active filter achieves better output voltage regulation compared to other topologies and can be used as grid interface

Design and implementation of hybrid vehicle using control of DC electric motor

The electric motors and its control technology are key components of hybrid electric vehicles (HEVs). Control of the electric motor is a fundamental issue for traction application in electric vehicles and HEVs. This paper presents the design, development and implementation of a hybrid vehicle using both an electric motor and petrol engine to increase efficiency and decrease carbon footprint. Initially, a prototype of a HEV is designed and the performance values are calculated, before a control system is developed and implemented to control the DC motor speed using a microcontroller as the vehicle’s electronic control unit along with simple proportional integral derivative (PID) control using speed as a feedback mechanism. The prototype made incorporated voltage, current, speed and torque sensors for feedback resulting in a closed loop control system which successfully matched the speed input of a user-controlled pedal sensor. A user interface was developed to show the driver of the vehicle key variables such as the revolutions per minute (RPM) of the motor, the speed of the vehicle along with the current being drawn, and the voltage applied to the motor with overall power. To output a variable voltage from the Arduino, a digital output was used with pulse width modulation (PWM) capabilities in order to provide a variable DC voltage to the speed controller

Spatial and Social Paradigms for Interference and Coverage Analysis in Underlay D2D Network

The homogeneous Poisson point process (PPP) is widely used to model spatial distribution of base stations and mobile terminals. The same process can be used to model underlay device-to-device (D2D) network, however, neglecting homophilic relation for D2D pairing presents underestimated system insights. In this paper, we model both spatial and social distributions of interfering D2D nodes as proximity based independently marked homogeneous Poisson point process. The proximity considers physical distance between D2D nodes whereas social relationship is modeled as Zipf based marks. We apply these two paradigms to analyze the effect of interference on coverage probability of distance-proportional power-controlled cellular user. Effectively, we apply two type of functional mappings (physical distance, social marks) to Laplace functional of PPP. The resulting coverage probability has no closed-form expression, however for a subset of social marks, the mark summation converges to digamma and polygamma functions. This subset constitutes the upper and lower bounds on coverage probability. We present numerical evaluation of these bounds on coverage probability by varying number of different parameters. The results show that by imparting simple power control on cellular user, ultra-dense underlay D2D network can be realized without compromising the coverage probability of cellular user.Comment: 10 pages, 10 figure

Using A Genre-Based Approach To Improving Islamic University Students’ Writing Ability & Hots

This study aims to determine the effect of genre-based and conventional approaches on students' writing skills and HOTS. This study uses a quantitative design with a quasi-experimental method conducted at IAIN Palopo, South Sulawesi, Indonesia. Sixty-two students from two classes were selected as research participants by dividing them into two groups, namely the experimental and control groups. Data were collected using two instruments: the writing assessment rubric and HOTS. The data that has been collected is then analyzed quantitatively by running the MANOVA test on SPSS 24.00. The results showed that the genre-based approach in the experimental group outperformed the control group, which used the conventional method to improve students' writing skills and HOTS

Separation Framework: An Enabler for Cooperative and D2D Communication for Future 5G Networks

Soaring capacity and coverage demands dictate that future cellular networks need to soon migrate towards ultra-dense networks. However, network densification comes with a host of challenges that include compromised energy efficiency, complex interference management, cumbersome mobility management, burdensome signaling overheads and higher backhaul costs. Interestingly, most of the problems, that beleaguer network densification, stem from legacy networks' one common feature i.e., tight coupling between the control and data planes regardless of their degree of heterogeneity and cell density. Consequently, in wake of 5G, control and data planes separation architecture (SARC) has recently been conceived as a promising paradigm that has potential to address most of aforementioned challenges. In this article, we review various proposals that have been presented in literature so far to enable SARC. More specifically, we analyze how and to what degree various SARC proposals address the four main challenges in network densification namely: energy efficiency, system level capacity maximization, interference management and mobility management. We then focus on two salient features of future cellular networks that have not yet been adapted in legacy networks at wide scale and thus remain a hallmark of 5G, i.e., coordinated multipoint (CoMP), and device-to-device (D2D) communications. After providing necessary background on CoMP and D2D, we analyze how SARC can particularly act as a major enabler for CoMP and D2D in context of 5G. This article thus serves as both a tutorial as well as an up to date survey on SARC, CoMP and D2D. Most importantly, the article provides an extensive outlook of challenges and opportunities that lie at the crossroads of these three mutually entangled emerging technologies.Comment: 28 pages, 11 figures, IEEE Communications Surveys & Tutorials 201

Wheat Productivity, Efficiency, and Sustainability: A Stochastic Production Frontier Analysis

This paper uses the farm-level survey data to estimate the stochastic frontier production function incorporating inefficiency effects. Sufficient evidence of positive relationship between wheat productivity and higher and balanced use of fertiliser nutrients was present. The productivity showed an inverse relationship with the proportionate farm area allocated to rice production and illustrated no association with the proportion of farm area under cotton. The average technical efficiency at wheat farms was about 68 percent. An inverse relationship was observed between technical efficiency and farm size. The farmers with greater access to credit and located closer to the markets were found more efficient. The small farmers are not only producing at a lower level but are also operating relatively farther from the production frontier. The results also revealed that wheat growers in Punjab are comparatively more efficient than their counterparts in Sindh and NWFP.stochastic frontier production function; technical efficiency; small farmer; Pakistan; productivity

Pengaruh Tingkat Inflasi dan Nilai Tukar Rupiah terhadap Harga Saham Perusahaan Bank BUMN yang terdaftar di Bursa Efek Indonesia

Penelitian ini bertujuan untuk mengetahui hubungan antara variabel tingkat inflasi dan nilai tukar dalam mempengaruhi harga saham. Untuk mencapai tujuan tersebut digunakan jenis penelitian deskriptif kausal. Populasi penelitian ini adalah data tingkat inflasi dan nilai tukar rupiah dan harga saham bank BUMN yang terdaftar di Bursa Efek Indonesia. Adapun teknik pengambilan sampel yang dipakai adalah purposive sampling, yakni data tingkat inflasi dan nilai tukar dan harga saham tahun 2015. Data dikumpulkan dengan teknik dokumentasi dan diolah dengan menggunakan uji statistik, analisis regresi berganda, analisis koefisien determinasi, uji-t dan uji-f. Dengan hipotesis bahwa secara simultan tingkat inflasi dan nilai tukar rupiah berpengaruh terhadap harga saham (H1) dan inflasi memberikan pengaruh yang lebih besar terhadap harga saham (H2). Dari hasil uji yang dilakukan menunjukkan (a) antara variabel tidak terdapat multikolonieritas di dalam hasil regresi tersebut, (b) menunjukkan tidak terdapat autokorelasi dan (c) data dalam penelitian ini berdistribusi normal. Hasil analisis regresi berganda menunjukkan Y= 0,971-0,267X1-0,402X2 menunjukkan bahwa nilai tukarlah yang paling dominan dalam mempengaruhi harga saham sebesar 0,402%, serta didapatkan bahwa tingkat inflasi dan nilai tukar rupiah berpengaruh terhadap harga saham secara simultan dan pengaruhya sebesar 32%. Maka dapat disimpulkan bahwa hipotesis 1 (H1) diterima dan hipotesis 2 (H2) tertolak. Kata kunci: Inflasi, Nilai Tukar, Harga Saha

Intracell interference characterization and cluster interference for D2D communication

The homogeneous spatial Poisson point process (SPPP) is widely used for spatial modeling of mobile terminals (MTs). This process is characterized by a homogeneous distribution, complete spatial independence, and constant intensity measure. However, it is intuitive to understand that the locations of MTs are neither homogeneous, due to inhomogeneous terrain, nor independent, due to homophilic relations. Moreover, the intensity is not constant due to mobility. Therefore, assuming an SPPP for spatial modeling is too simplistic, especially for modeling realistic emerging device-centric frameworks such as device-to-device (D2D) communication. In this paper, assuming inhomogeneity, positive spatial correlation, and random intensity measure, we propose a doubly stochastic Poisson process, a generalization of the homogeneous SPPP, to model D2D communication. To this end, we assume a permanental Cox process (PCP) and propose a novel Euler-Characteristic-based approach to approximate the nearest-neighbor distribution function. We also propose a threshold and spatial distances from an excursion set of a chi-square random field as interference control parameters for different cluster sizes. The spatial distance of the clusters is incorporated into a Laplace functional of a PCP to analyze the average coverage probability of a cellular user. A closed-form approximation of the spatial summary statistics is in good agreement with empirical results, and its comparison with an SPPP authenticates the correlation modeling of D2D nodes

Penelusuran Alumni Sebagai Upaya Peningkatan Profil Program Keahlian Teknik Komputer Dan Jaringan di SMK Muhammadiyah 1 Sukoharjo

Penelusuran alumni program keahlian Teknik Komputer dan Jaringan (TKJ) di SMK Muhammadiyah 1 Sukoharjo bertujuan  untuk: 1) mengetahui gambaran profil  lulusannya; 2) relevansi program keahlian dengan kebutuhan pasar kerja; 3) tanggapan pengguna alumni. Penelitian  ini  merupakan tracer  study dengan  pendekatan  analisis deskriptif kualitatif. Pelaksanaan tracer study dilakukan dengan metode survei. Analisis yang dilakukan dengan presentase dan menggunakan 3 tahapan yaitu reduksi data, penyajian data dan pengambilan kesimpulan. Hasil penelitian tracer study memberi gambaran bahwa dalam masa tunggu 6 bulan sebanyak 58% alumni tercatat bekerja, kuliah dan berwirausaha, dengan pendapatan 1,3 juta - 5 juta/bulan. Dengan relevansi kompetensi dengan kebutuhan pasar sebesar 49%. Kuliah atau studi lanjut masih menjadi mayoritas alumni. Stackeholder pengguna alumni menyarankan untuk peningkatan profil alumni program keahlian TKJ SMK Muhammadiyah 1 Sukoharjo dengan penambahan kompetensi pemograman (coding), design, digital marketing untuk membekali alumni supaya bisa fleksible dalam mencari pekerjaan dan saran dari alumni perlu penambahan rasio peralatan praktik jaringan.