The Experts below are selected from a list of 126 Experts worldwide ranked by ideXlab platform
Amir Masoud Rabiei - One of the best experts on this subject based on the ideXlab platform.
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a fair relay selection scheme for a df cooperative network with spatially random relays
IEEE Transactions on Vehicular Technology, 2017Co-Authors: Masoumeh Sadeghi, Amir Masoud RabieiAbstract:A new, fair relay selection scheme is proposed for a dual-hop one-way decode-and-forward network with randomly distributed relays, in a general fading environment. Most of the reported works in the literature achieve fairness at the expense of degrading the outage probability performance. In addition, they often assume that the number and locations of the relays are fixed. In contrast, the proposed scheme achieves fairness in a random field of relays without deteriorating the outage probability performance. In this scheme, each relay maintains a Countdown Timer whose initial value is a function of the relay location and a tunable parameter that controls the level of fairness. The optimum value of this parameter is evaluated in an offline manner so as to achieve fairness by making the average powers consumed by the relays as close as possible. An integral-form analytical expression is derived for the average power consumed by each relay. This expression is then used to show the superiority of the proposed scheme over opportunistic relaying and random relay selection schemes in having better fairness performance.
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a fair relay selection scheme for a df cooperative network with spatially random relays
arXiv: Networking and Internet Architecture, 2016Co-Authors: Masoumeh Sadeghi, Amir Masoud RabieiAbstract:A new, fair relay selection scheme is proposed for a dual-hop decode-and-forward network with randomly-distributed relays. Most of the reported works in the literature achieve fairness at the expense of degrading the outage probability performance. In addition, they often assume that the number and locations of the relays are known. In contrast, the proposed scheme achieves fairness in a random field of relays without deteriorating the outage probability performance. In this scheme, each relay maintains a Countdown Timer whose initial value is a function of the relay location and a tunable parameter which controls the level of fairness. The optimum value of this parameter is evaluated in an offline manner so as to achieve fairness by making the average powers consumed by the relays as close as possible. An exact analytical expression is derived for the average power consumed by each relay. This expression is then used to show the superiority of the proposed scheme over opportunistic relaying and random relay selection schemes.
Masoumeh Sadeghi - One of the best experts on this subject based on the ideXlab platform.
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a fair relay selection scheme for a df cooperative network with spatially random relays
IEEE Transactions on Vehicular Technology, 2017Co-Authors: Masoumeh Sadeghi, Amir Masoud RabieiAbstract:A new, fair relay selection scheme is proposed for a dual-hop one-way decode-and-forward network with randomly distributed relays, in a general fading environment. Most of the reported works in the literature achieve fairness at the expense of degrading the outage probability performance. In addition, they often assume that the number and locations of the relays are fixed. In contrast, the proposed scheme achieves fairness in a random field of relays without deteriorating the outage probability performance. In this scheme, each relay maintains a Countdown Timer whose initial value is a function of the relay location and a tunable parameter that controls the level of fairness. The optimum value of this parameter is evaluated in an offline manner so as to achieve fairness by making the average powers consumed by the relays as close as possible. An integral-form analytical expression is derived for the average power consumed by each relay. This expression is then used to show the superiority of the proposed scheme over opportunistic relaying and random relay selection schemes in having better fairness performance.
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a fair relay selection scheme for a df cooperative network with spatially random relays
arXiv: Networking and Internet Architecture, 2016Co-Authors: Masoumeh Sadeghi, Amir Masoud RabieiAbstract:A new, fair relay selection scheme is proposed for a dual-hop decode-and-forward network with randomly-distributed relays. Most of the reported works in the literature achieve fairness at the expense of degrading the outage probability performance. In addition, they often assume that the number and locations of the relays are known. In contrast, the proposed scheme achieves fairness in a random field of relays without deteriorating the outage probability performance. In this scheme, each relay maintains a Countdown Timer whose initial value is a function of the relay location and a tunable parameter which controls the level of fairness. The optimum value of this parameter is evaluated in an offline manner so as to achieve fairness by making the average powers consumed by the relays as close as possible. An exact analytical expression is derived for the average power consumed by each relay. This expression is then used to show the superiority of the proposed scheme over opportunistic relaying and random relay selection schemes.
Slamet Jauhari Legowo - One of the best experts on this subject based on the ideXlab platform.
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studi variasi keberangkatan lalu lintas dan perbandingan arus jenuh metode time slice dengan arus jenuh mkji 1997 pada simpang bersinyal dengan short time Countdown Timer
Matriks Teknik Sipil, 2018Co-Authors: Tri Utamy Yohana Panjaitan, Amirotul M H Mahmudah, Slamet Jauhari LegowoAbstract:Pada jalan raya, titik konflik yang paling banyak ditemui yaitu pada simpang. Salah satu upaya untuk mengurangi titik konflik adalah dengan penambahan lampu lalu lintas. Perangkat lain yang dapat ditambahkan pada simpang adalah Countdown Timer. Countdown Timer merupakan perangkat tambahan yang berfungsi memberikan informasi mengenai durasi waktu sinyal dari lampu lalu lintas. Akan tetapi, penambahan Countdown Timer ternyata menyebabkan timbulnya variasi pada keberangkatan lalu lintas atau kendaraan (Cong dkk; 2012). Penelitian ini bertujuan untuk mengetahui variasi pada waktu keberangkatan dan nilai arus jenuh dasar per meter (S 0 /m) pada simpang bersinyal dengan Countdown Timer . Data diperoleh di Simpang Sate Sumber, Simpang Polres Karanganyar, dan Simpang Tugu Wisnu yang dilakukan pada jam puncak dan jam tidak puncak. Data variasi waktu keberangkatan dianalisis menggunakan analisis statistic, sementara data arus jenuh meggunakan metode time slice . Berdasarkan hasil analisis, diketahui variasi waktu keberangkatan yang terjadi berupa percepatan waktu keberangkatan pada Simpang Sate Sumber dan perlambatan waktu keberangkatan pada Simpang Polres Karanganyar dan Simpang Tugu Wisnu. Nilai S 0 /m yang diperoleh pada semua simpang baik pada jam puncak tidak ada yang memenuhi standar S 0 /m MKJI 1997 yaitu sebesar 600.
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variasi waktu keberangkatan arus kendaraan dan arus jenuh per meter s0 m pada simpang bersinyal dengan full time Countdown Timer
Matriks Teknik Sipil, 2018Co-Authors: Ginung Pratina, Amirotul M H Mahmudah, Slamet Jauhari LegowoAbstract:Countdown Timer merupakan perangkat tambahan pada lampu lalu lintas, tujuannya memberi informasi kepada pengendara tentang durasi waktu dari lampu lalu lintas. Menurut Cong dkk (2012), adanya Countdown Timer ternyata menimbulkan beberapa dampak lalu lintas, diantaranya pergerakan keberangkatan kendaraan sebelum waktu hijau dengan waktu keberangkatan yang bervariasi. Tujuan penelitian ini adalah untuk mengetahui terjadinya variasi waktu keberangkatan, faktor yang mempengaruhi, dan nilai S 0 /m pada simpang bersinyal dengan Countdown Timer . Lokasinya di Simpang Jimbaran FM, Simpang Genengan, dan Simpang Kelurahan Mojosongo. Data yang digunakan berupa data primer yang di peroleh secara langsung di lapangan dan data sekunder yang diperoleh dari instansi terkait. Penelitian ini menggunakan analisis statistik untuk variasi waktu keberangkatan dan time slice untuk arus jenuh. Hasil analisisnya, variasi waktu keberangkatan arus kendaraan yang terjadi, kecuali pada Simpang Jimbaran FM lengan pendekat Timur, mengalami percepatan keberangkatan arus kendaraan. Faktor pengaruh terjadinya variasi waktu keberangkatan arus kendaraan pada jam puncak adalah arus jenuh, sepeda motor, kendaraan ringan, dan S 0 /m, sedangkan pada jam tidak puncaknya adalah sepeda motor dan S 0 /m. Nilai S 0 /m yang diperoleh untuk semua lengan pendekat simpang baik pada jam puncak maupun jam tidak puncak, tidak ada yang sesuai dengan nilai S 0 /m standar MKJI 1997, sebesar 600.
Ginung Pratina - One of the best experts on this subject based on the ideXlab platform.
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variasi waktu keberangkatan arus kendaraan dan arus jenuh per meter s0 m pada simpang bersinyal dengan full time Countdown Timer
Matriks Teknik Sipil, 2018Co-Authors: Ginung Pratina, Amirotul M H Mahmudah, Slamet Jauhari LegowoAbstract:Countdown Timer merupakan perangkat tambahan pada lampu lalu lintas, tujuannya memberi informasi kepada pengendara tentang durasi waktu dari lampu lalu lintas. Menurut Cong dkk (2012), adanya Countdown Timer ternyata menimbulkan beberapa dampak lalu lintas, diantaranya pergerakan keberangkatan kendaraan sebelum waktu hijau dengan waktu keberangkatan yang bervariasi. Tujuan penelitian ini adalah untuk mengetahui terjadinya variasi waktu keberangkatan, faktor yang mempengaruhi, dan nilai S 0 /m pada simpang bersinyal dengan Countdown Timer . Lokasinya di Simpang Jimbaran FM, Simpang Genengan, dan Simpang Kelurahan Mojosongo. Data yang digunakan berupa data primer yang di peroleh secara langsung di lapangan dan data sekunder yang diperoleh dari instansi terkait. Penelitian ini menggunakan analisis statistik untuk variasi waktu keberangkatan dan time slice untuk arus jenuh. Hasil analisisnya, variasi waktu keberangkatan arus kendaraan yang terjadi, kecuali pada Simpang Jimbaran FM lengan pendekat Timur, mengalami percepatan keberangkatan arus kendaraan. Faktor pengaruh terjadinya variasi waktu keberangkatan arus kendaraan pada jam puncak adalah arus jenuh, sepeda motor, kendaraan ringan, dan S 0 /m, sedangkan pada jam tidak puncaknya adalah sepeda motor dan S 0 /m. Nilai S 0 /m yang diperoleh untuk semua lengan pendekat simpang baik pada jam puncak maupun jam tidak puncak, tidak ada yang sesuai dengan nilai S 0 /m standar MKJI 1997, sebesar 600.
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analisis variasi waktu keberangkatan arus kendaraan dan arus jenuh pada simpang bersinyal yang dilengkapi dengan full time Countdown Timer
2018Co-Authors: Ginung PratinaAbstract:Countdown Timer merupakan perangkat tambahan pada lampu lalu lintas, yang bertujuan untuk memberikan informasi kepada para pengendara tentang durasi waktu dari lampu lalu lintas. Cong dkk (2012) menyampaikan bahwa dengan penambahan Countdown Timer ternyata menimbulkan beberapa dampak lalu lintas. Salah satu contoh adalah terjadinya pergerakan keberangkatan kendaraan sebelum waktu hijau dengan waktu keberangkatan yang berbeda-beda, inilah yang kemudian mengindikasikan bahwa pada simpang tersebut telah terjadi adanya variasi waktu keberangkatan arus kendaraan. Penelitian ini dilakukan untuk mengetahui variasi waktu keberangkatan yang terjadi, faktor pengaruh terjadinya variasi waktu keberangkatan, dan besarnya arus jenuh yang terjadi yang terjadi pada simpang bersinyal yang dilengkapi dengan Countdown Timer. Penelitian dilakukan di Simpang Jl. Monginsidi – Jl. DI Panjaitan, Simpang Jl. Sumpah Pemuda – Jl. Letjen Sutoyo, dan Simpang Jl. Sumpah Pemuda – Jl. Tangkuban Perahu. Data yang digunakan pada penelitian ini berupa data primer yang di peroleh di lapangan dan data sekunder yang diperoleh dari instansi terkait. Untuk teknik pengambilan data lapangan dengan menggunakan rekaman video dan pengukuran langsung. Metode yang digunakan adalah analisis statistik untuk pergeseran waktu keberangkatan dan time slice 6 interval untuk arus jenuh.Berdasarkan analisis, didapatkan bahwa untuk variasi waktu keberangkatan arus kendaraan yang terjadi, kecuali pada Simpang Jl. Monginsidi – Jl. DI Panjaitan lengan pendekat Timur, mengalami percepatan keberangkatan arus kendaraan. Terjadinya percepatan keberangkatan arus kendaraan ini menunjukan bahwa dengan adanya Countdown Timer justru menimbulkan banyak pelanggaran terhadap lampu lalu lintas, yang mana penyebabnya adalah perilaku dari pengendaranya. Faktor yang dapat mempengaruhi terjadinya variasi waktu keberangkatan arus kendaraan pada jam puncak adalah arus jenuh, sepeda motor, kendaraan ringan, dan S0/m, sedangkan untuk jam tidak puncaknya adalah sepeda motor dan S0/m. Nilai S0/m yang diperoleh untuk semua lengan pendekat simpang baik pada jam puncak maupun jam tidak puncak, tidak ada yang sesuai dengan nilai S0/m standar MKJI 1997, sebesar 600.
Yaping Zhang - One of the best experts on this subject based on the ideXlab platform.
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comparative analysis of driver s brake perception reaction time at signalized intersections with and without Countdown Timer using parametric duration models
Accident Analysis & Prevention, 2016Co-Authors: Yaping Zhang, Yiming BieAbstract:Countdown Timers display the time left on the current signal, which makes drivers be more ready to react to the phase change. However, previous related studies have rarely explored the effects of Countdown Timer on driver's brake perception-reaction time (BPRT) to yellow light. The goal of this study was therefore to characterize and model driver's BPRT to yellow signal at signalized intersections with and without Countdown Timer. BPRT data for "first-to-stop" vehicles after yellow onset within the transitional zone were collected through on-site observation at six signalized intersections in Harbin, China. Statistical analysis showed that the observed 15th, 50th, and 85th percentile BPRTs without Countdown Timer were 0.52, 0.84, and 1.26s, respectively. The observed 15th, 50th, and 85th percentile BPRTs with Countdown Timer were 0.32, 1.20, and 2.52s, respectively. Log-logistic distribution appeared to best fit the BPRT without Countdown Timer, while Weibull distribution seemed to best fit the BPRT with Countdown Timer. After that, a Log-logistic accelerated failure time (AFT) duration model was developed to model driver's BPRT without Countdown Timer, whereas a Weibull AFT duration model was established to model driver's BPRT with Countdown Timer. Three significant factors affecting the BPRT identified in both AFT models included yellow-onset distance from the stop line, yellow-onset approach speed, and deceleration rate. No matter whether the presence of Countdown Timer or not, BPRT increased as yellow-onset distance to the stop line or deceleration rate increased, but decreased as yellow-onset speed increased. The impairment of driver's BPRT due to Countdown Timer appeared to increase with yellow-onset distance to the stop line or deceleration rate, but decrease with yellow-onset speed. An increase in driver's BPRT because of Countdown Timer may induce risky driving behaviors (i.e., stop abruptly, or even violate traffic signal), revealing a weakness of Countdown Timer in traffic safety aspect.
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Effects of digital Countdown Timer on intersection safety and efficiency: A systematic review.
Traffic Injury Prevention, 2015Co-Authors: Chuanyun Fu, Weiwei Qi, Yaping Zhang, Shaowu ChengAbstract:ABSTRACTObjective: To investigate the available evidence referring to the effectiveness of digital Countdown Timers (DCTs) in improving the safety and operational efficiency of signalized intersection.Methods: A systematic review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) statement guidelines. Relevant literature was searched from electronic databases using key terms. Based on study selection and methodological quality assessment, 14 studies were included in the review. Findings of the studies were synthesized in a narrative analysis.Results: Three types of DCT had different effects on intersection safety and operational efficiency. Green signal Countdown Timers (GSCTs) reduced red light violations, type I dilemma zone distributions, and rear-end collision likelihood but increased crossing after yellow onset and had mixed impacts on type II dilemma zone distributions and intersection capacity. In contrast, red signal Countdown Timers (RSCTs) ...
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effects of Countdown Timer on yellow light running an empirical study
2015Co-Authors: Yaping Zhang, Ting PengAbstract:Yellow light violation is exacerbated by the deficiency in the definition of yellow light function from Chinese road traffic safety law and no penalty to such violators. Last January, the "embarrassment" of a new traffic regulation pertaining to deter drivers from running yellow light made Countdown Timer be the better option to prevent this risky behavior. Since then, more and more Countdown Timers have been installed in China cities. However, the actual influences on yellow light running of Countdown Timer are still unclear, though there are very few relevant studies. The current study attempts to uncover more deeply the effects on yellow light running of Countdown Timer. Data on the number of yellow light running occurrence, entry time, and entry speed of vehicles crossing the stop line after yellow light onset were collected at four comparable intersection approaches located in Harbin, China. Statistical analysis results show that Countdown Timer has limited positively impact on the reduction of yellow light running, but no significant effect on entry speed. Furthermore, Countdown Timer leads to increase entrance into the intersection during the earlier portions of yellow signal.
