A Channel Coding Perspective of Collaborative Filtering

We consider the problem of collaborative filtering from a channel coding perspective. We model the underlying rating matrix as a finite alphabet matrix with block constant structure. The observations are obtained from this underlying matrix through a discrete memoryless channel with a noisy part representing noisy user behavior and an erasure part representing missing data. Moreover, the clusters over which the underlying matrix is constant are {\it unknown}. We establish a sharp threshold result for this model: if the largest cluster size is smaller than $C_1 \log(mn)$ (where the rating matrix is of size $m \times n$), then the underlying matrix cannot be recovered with any estimator, but if the smallest cluster size is larger than $C_2 \log(mn)$, then we show a polynomial time estimator with diminishing probability of error. In the case of uniform cluster size, not only the order of the threshold, but also the constant is identified.Comment: 32 pages, 1 figure, Submitted to IEEE Transactions on Information Theor

Analisis Kinerja Sistem Doppler VHF Omnidirectional Range dan Distance Measuring Equipment pada Navigasi Penerbangan

Navigasi udara merupakan kegiatan untuk mengarahkan transportasi udara dari satu tempat ke tempat yang lain agar tidak keluar dari jalurnya. Sistem transmisi sinyal pada Doppler VHF Omnidirectional Range (DVOR) belum sepenuhnya optimal karena persentase sinyal modulasinya sering mengalami peningkatan yang berakibat pada munculnya kondisi sinyal over-modulated. Deteksi sinyal interogasi maupun sinyal balasan pada Distance Measuring Equipment (DME) mengalami hambatan disebabkan oleh waktu tunda dan jarak pulsa yang tidak sesuai. Pada penelitian ini, akan dilakukan analisis kinerja sistem DVOR-DME dengan membandingkan nilai parameter dan nilai kondisi normal. Berdasarkan analisis kinerja sistem, didapatkan bahwa sistem DVOR-DME AirNav Indonesia Distrik Tanjungpinang beroperasi dengan normal. Nilai optimal 30Hz MOD dan 9960Hz MOD pada DVOR berada pada rentang nilai normal yaitu sebesar 30%. Nilai optimal delay dan spacing pada DME berada pada rentang nilai delay normal dan nilai spacing normal yaitu sebesar 50,01 μs dan 12,02 μs

Cellular Multihop Networks: State of the Art

This paper presents the summary of some research in the area of cellular multihop networks that contains the improvement in network performance also the difficulties and the complexities of the networks. The combination of two different networks, mobile cellular networks and WLAN ad hoc networks will be presented. The main purpose of the combination is to minimize the weaknesses of both network types when they are deployed separately. By having this combination then it is possible to provide higher mobility for WLAN ad hoc networks user and higher data transfer rate for cellular network users in multimedia applications. The cellular multihop networks will reduce blocking probability, balance the cells load and increase the network capacities. Although there are improvement on the performance of the combine networks, but there are additional aspects that should be considered seriously, especially for WLAN ad hoc users. Authentication, Authorization and Accounting (AAA) functions, the dynamic routing and relay path discovery, maintenance and security issues are aspects to be considered for cellular multihop network

Procrastination in Completing the Thesis

The purpose of this study is to describe and understand colleger academic procrastination in completing their thesis. In this study, academic procrastination in completing the thesis is generally defined as a form of deliberate delays and repeated it in completing a task or duty, either when starting or finishing thesis related to the academic field.In this study, the method used is a case study. Used two subjects and those who closest to the subject that is often interact with the subject so it can help enriching this research data. Based on the results of interviews and observations of the study, it can be concluded that the procrastination process of UNDIP Psychology colleger who was working on the thesis is influenced by several factors, internal and external. Internal factors include interpreting the subject thesis, how far the subject\u27s know the benefit of the thesis for them, subject\u27s perception toward the thesis, and subject\u27s personality like need of achievement, need of competition, superiority, self over confidence, poor self-regulation, lack of seriousness while working on the thesis, internal conflicts occurring within the subject, perfectionist, lazy, comfortable in certain situations, external locus of control, interpersonal dependency, and the subject\u27s ability to adapt.Meanwhile, external factors that affect procrastination process of UNDIP Psychology colleger who was working on the thesis is thesis supervisor, high expectations towards thesis supervisor and the conflict with the thesis supervisor, stressors that appears like feeling worry being blame by the thesis supervisor, and having differences of opinion with the thesis supervisor, thesis bureau or bureaucracy, a standard system that the subject feels quite high compared with other faculties and other universities, other barriers, such as lost social support, social pressure, trouble getting a thesis supervisor, difficulty in obtaining subjects, title changed many times, difficult to meet the supervisor, difficult to get a reference, and less guidance from thesis supervisor

Perbedaan Stres Akulturatif Antara Mahasiswa Papua Dan Mahasiswa Batak Di Kota Semarang

Stres akulturatif adalah respon fisik dan psikologis serta perilaku yang dirasakan individu terhadap peristiwa yang dianggap sebagai tekanan yang berasal dari akulturasi dan dapat mengakibatkan penurunan status kesehatan mental, perasaan marjinalisasi dan alienasi, simtom psikosomatis yang meningkat dan kebingungan jati diri. Penelitian ini bertujuan untuk menguji secara empirik perbedaan stres akulturatif antara mahasiswa Papua dan mahasiswa Batak di Kota Semarang. Populasi dalam penelitian ini adalah mahasiswa Papua dan mahasiswa Batak angkatan 2013. Subjek penelitian berjumlah 80 terdiri dari 45 mahasiswa Batak asli dan 35 mahasiswa Papua asli yang diperoleh melalui teknik Accidental Sampling. Metode analisis data yang digunakan adalah teknik uji-t. Alat pengumpulan data dalam penelitian ini adalah Skala Stres Akulturatif (42 item dengan α = 0,920). Hasil penelitian ini menunjukkan nilai t = 6,454 dengan p = 0,000 (

Analisis Pengaruh Atribut Produk Terhadap Loyalitas Nasabah (Studi Pada Tabungan Britama Bri Kantor Cabang Pattimura Semarang)

Competition in today's business world is getting tougher. this affects particularly kapadaBRI in 2012. BRI bank customers BritAma savings each month fluctuated. AlthoughBritAma already provide product attributes that can compete with other banks, but stillcan not reach the target. This study aims to research how much influence of the qualityproduct, features product, and design product by BritAma to customer loyalty BRIPattimura Semarang.The population in this study are BritAma customer of BRI Pattimura Semarang. Thesample in this study were randomly conducted using non probability sampling techniqueand accidental sampling method. The analysis used in this study is multiple liniearregression analysis, by using the stage of tes validity, test reliability, and classicalassumption tes. And then the hypothesis is evidenced by t test, F test, and coefficient ofdetermination (R²).The result of multiple liniear regression analysis that has been done shows that allindependent variables, the quality product, fitur product, and desaign product have a positiveinfluence on the dependent variable, customer loyalty. The independent variable is the mostinfluential of the dependent variable is the variable fitur product (0,433), followed by qualityproduct (0,306), and then desaign product (0,274). And the coefficient of determination(adjusted R²) is 0,503. This means that 50,3% customer loyalty is affected by variable qualityproduct, fitur product, and desaign product. While the ramaining 49,7% is influenced byother variables that are not addressed in this study

Implementasi Dan Evaluasi Kinerja Direct Sequence Spread Spectrum Menggunakan Wireless Open-Access Research Platform (WARP)

Dalam sistem komunikasi nirkabel, khususnya pada dunia komunikasi taktis atau militer, salah satu yang harus dihadapi adalah gangguan jamming.Salah satu sistem yang dapat mengatasi masalah tersebut adalah Direct Sequence Spread Spectrum (DSSS) dimana informasi akan dikalikan secara langsung dengan pseudo-noise sequence yang mempunyai laju chip jauh lebih besar.Sistem ini dapat diimplementasikan pada Wireless Open-Access Research Platform (WARP) yang merupakan salah satu dari jenis Software Define Radio (SDR).Modul WARP mampu diprogram secara langsung dengan software MATLAB.Kinerja sistem terbaik didapatkan ketika daya sinyal jamming lebih kecil atau sama dengan daya sinyal carrier sistem DSSS. Pada Single Tone Jamming (STJ) sistem akan mencapai nilai BER 10E-3 saat daya sinyal jamming 125 % dari daya sinyal sistem DSSS, sedangkan pada Multi Tone Jamming (MTJ) sistem akan mencapai BER 10E-3 saat daya sinyal jamming 100 % dari daya sistem DSSS

Implementasi Modulasi Dan Demodulasi GMSK Pada DSK TMS320C6416T

Gaussian minimum shift keying (GMSK) adalah teknik modulasi yang mengurangi spectrum sidelobe pada MSK dengan cara melewatkan sinyal NRZ ke filter LPF Gaussian sehingga menimbulkan kelebihan dan kekurangan tertentu. Modulator dan demodulator GMSK dapat diprogram dengan menggunakan DSP processor. DSK TMS320C6416T adalah salah satu board/hardware untuk memproses sinyal digital yang termasuk dalam platform TMS320C6000. Aplikasi DSP processor ini bekerja pada frekuensi 0-96 kHz yang merupakan standar dalam sistem telekomunikasi. Tugas Akhir ini melakukan implementasi modulasi dan demodulasi GMSK secara real ke dalam DSP Starter Kit TMS320C6416T. Pemodelan sistemnya di-generate dengan menggunakan software Simulink MATLAB. Simulasi dan implementasi sistem yaitu dengan input bernoulli binary generator, pulse generator, dan random integer. Pengujian dilakukan untuk mengetahui kinerja DSK TMS320C6416T secara real terhadap parameter GMSK yang diujikan seperti efisiensi bandwidth dan karakteristik ISI terhadap Perubahan nilai bandwidth/bit time (BT) serta kinerja BER, terhadap variasi nilai Eb/N0 dan BT yang dilakukan dengan mengirimkan 100.000 bit yang ditampilkan pada blok display Simulink MATLAB dan Visual Analyser. Kinerja terbaik terdapat pada implementasi yang menggunakan nilai BT sama dengan 1 dan nilai Eb/N0 sama dengan 15 dan kinerja terburuk terdapat pada implementasi dengan nilai BT dan nilai Eb/N0 yang semakin menurun mendekati 0