80 research outputs found
Indoor Wireless Communications using Slotted ISMA protocols
No full textThe performance of the Slotted ISMA protocols in Rician fading channel for Indoor Wireless communications considering Pico Cellular systems have been analyzed in this thesis. The throughput of Slotted nonpersistant Inhibit Sense Multiple Access (np-ISMA), Slotted 1-persistent ISMA (1p-ISMA) and Slotted np-ISMA\CD (Collision Detection) is investigated in the presence of n-interfering signals whose random amplitudes are considered as Rician distributed. Numerical results are presented, indicating the effect of propagation impairments on channel capacity. The results are of importance for mobile networks and indoor wireless office communications.Electrical Engineering, Mathematics and Computer ScienceTelecommunicatie- en Verkeersbegeleidingssysteme
Unslotted Hybrid CDMA/ISMA Protocol for Indoor Wireless Computer Communications
No full textA hybrid Code Division Multiple Access / Inhibit Sense Multiple Access (CDMA/ISMA) protocol has been proposed as an effective multiple access scheme for Indoor Wireless Computer Communications. This new protocol combines the advantages of both CDMA and ISMA into one protocol. On the one hand the ISMA protocol introduces a limitation to the number of simultaneous accesses to the transmission channel. On the other hand the CDMA protocol introduces an improvement to the packet survival chance. It is shown that the performance of the hybrid protocol is indeed better than CDMA only. In addition, code sharing can be applied to reduce hardware cost. The slotted hybrid CDMA/ISMA protocol using the p-persistent ISMA scheme has already been analysed. In this report, we investigate the hybrid protocol using the unslotted non-persistent ISMA scheme. The analysis is done for a star-connected multiple access wireless computer network. The performance comparison between the slotted and unslotted hybrid CDMA/ISMA protocol is evaluated in terms of throughput and delay using computer simulation and mathematical analysis.Electrical Engineering, Mathematics and Computer ScienceTelecommunicatie- en Verkeersbegeleidingssysteme
Performance Analysis of Slotted ISMA Protocols for Mobile Communications on a Three Lane Motorway
No full textA slotted ISMA protocol has been proposed for using with the communication channel from vehicles to a base station near the motorway. In this report the performance of this channel using the proposed protocol is analysed. Three slotted ISMA protocols can be distinguished, namely: • p-persistent slotted ISMA; • 1-persistent slotted ISMA; • non-persistent slotted ISMA. The performance of the protocol has been measured in terms of the throughput and the packet delay of the communication channel. The system has been modelled by assuming a capture receiver at the base station. The vehicles are assumed to maintain constant velocities while moving in one direction inside a cell of 200 metres on a three-lane motorway. The distribution of the vehicle positions on the motorway has been considered. Also the influence of the packet length and collision detection ratio will be examined. Furthermore the integration of DECT with the designed system is investigated. The performance of the system has been investigated for three traffic types: light traffic, heavy traffic and queuing traffic.Applied SciencesElectrical EngineeringTelecommunications and Traffic-Control Systems Grou
Performance Analysis of a Hybrid ISMA/CDMA Protocol for Indoor Wireless Communication
No full textThe hostile transmission medium encountered in Indoor: Wireless Communications (IWC) requires the use of special communication protocols. In this report we investigate a combination of the Inhibit Sense Multiple Access (ISMA) and Code Division Multiple Access (CDMA) protocols. The ISMA protocol limits the number of simultaneous accesses to the transmission channel and the CDMA protocol improves the packet survival chance. With CDMA each bit is transmitted using several code bits, giving each signal has its own, easy to recognize, signature. Coding spreads the signal over a large transmission bandwidth, which makes it particularly resistant to fading and multipath propagation, two key factors which degrade network performance…Applied SciencesElectrical EngineeringTelecommunications and Traffic Control Systems Grou
Hybrid CDMA / ISMA Protocol in Rician Fading Channel in Indoor Wireles Data Communications
No full textThis thesis describes the performance analysis of a star-connected, indoor wireless computer data communication system using direct-sequence code division multiple access (DS-CDMA) and Hybrid CDMA / Inhibit Sense Multiple Access (ISMA) protocol. The channel performance is investigated in terms of bit error rate (BER) and the protocol performance is investigated in terms of traffic-throughput and throughput-delay characteristics. To enhance the performance, a diversity technique using Maximum Ratio Combining (MRC) is used. Comparison of the simulation results with the analytical results is also performed.Applied SciencesElectrical EngineeringTelecommunications and Traffic Control Systems Grou
Socioeconomic factors and renewable energy adoption in Pakistan and Türkiye
No full textPakistan and Türkiye rely heavily on imported fossil fuels to satisfy their energy needs. Pakistan is making progress towards addressing the energy scarcity by emphasising renewable energy sources in its existing infrastructure. In order to lessen Pakistan's energy problems, a number of projects—such as wind power and solar PV (photovoltaic) technologies—are either operational or in the process of being developed. By 2030, the new Pakistani government wants to raise the percentage of renewable energy in all electricity generation to 30%. However, Türkiye outperforms Pakistan in terms of renewable energy resources; the nation is home to 186 active wind power facilities, for instance. The complex interactions between socioeconomic variables and the uptake of renewable energy in the two very different contexts of Pakistan and Türkiye are examined in this study abstract. Comprehending the intricate socioeconomic processes becomes crucial as these countries struggle with the necessity of shifting to renewable energy sources. This study intends to uncover important factors impacting the adoption of renewable energy technology in both nations through a thorough analysis of the literature. Finding trends that influence the renewable energy landscape is the aim of this research, which analyses variables including public awareness, education, and income levels. In order to promote an equitable and successful transition, the abstract emphasises the significance of bridging the gap between socioeconomic issues and the creation of renewable energy policies. In the end, our research adds to the larger conversation about sustainable development by providing information that might guide focused groups in encouraging Pakistani and Turkish use of renewable energy.Pakistan ve Türkiye enerji ihtiyaçlarını karşılamak için büyük ölçüde ithal fosil yakıtlara bel bağlamaktadır. Pakistan, mevcut altyapısında yenilenebilir enerji kaynaklarına ağırlık vererek enerji kıtlığını giderme yolunda ilerleme kaydetmektedir. Pakistan'ın enerji sorunlarını azaltmak için rüzgar enerjisi ve güneş PV (fotovoltaik) teknolojileri gibi bir dizi proje ya faaliyete geçmiş ya da geliştirilme aşamasındadır. Yeni Pakistan hükümeti 2030 yılına kadar tüm elektrik üretiminde yenilenebilir enerji oranını %30'a çıkarmak istemektedir. Ancak Türkiye, yenilenebilir enerji kaynakları açısından Pakistan'ı geride bırakmaktadır; örneğin ülke 186 aktif rüzgar enerjisi tesisine ev sahipliği yapmaktadır. Bu çalışmada, sosyoekonomik değişkenler ile Pakistan ve Türkiye'nin iki farklı bağlamında yenilenebilir enerjinin benimsenmesi arasındaki karmaşık etkileşimler incelenmektedir. Karmaşık sosyoekonomik süreçlerin anlaşılması, bu ülkeler yenilenebilir enerji kaynaklarına geçiş zorunluluğu ile mücadele ederken çok önemli hale gelmektedir. Bu çalışma, literatürün kapsamlı bir analizi yoluyla her iki ülkede de yenilenebilir enerji teknolojisinin benimsenmesini etkileyen önemli faktörleri ortaya çıkarmayı amaçlamaktadır. Kamu bilinci, eğitim ve gelir düzeyleri gibi değişkenleri analiz eden bu araştırmanın amacı, yenilenebilir enerji ortamını etkileyen eğilimleri bulmaktır. Bu tez, eşitlikçi ve başarılı bir geçişi teşvik etmek için sosyoekonomik konular ile yenilenebilir enerji politikalarının oluşturulması arasındaki boşluğu doldurmanın önemini vurgulamaktadır. Sonuç olarak araştırmamız, Pakistan ve Türkiye'de yenilenebilir enerji kullanımının teşvik edilmesinde odak gruplara rehberlik edebilecek bilgiler sağlayarak sürdürülebilir kalkınma hakkındaki daha geniş tartışmalara katkıda bulunmaktadır
Throughput analysis of some mobile packet radio protocols in Rician fading Channels
No full textThe throughput of packet radio channels is investigated theoretically using the interference model in Rician fading environment. Three types of packet protocols are considered, namely: i) slotted ALOHA, ii) unslotted nonpersistent ISMA, and iii) slotted nonpersistent ISMA. Numerical results are presented, indicating the effect of propagation impairments on channel capacity. The results are of importance for mobile data networks, wireless office communications and other packet systems with contention-limited performance.Electrical Engineering, Mathematics and Computer ScienceTelecommunicatie- en Verkeersbegeleidingssysteme
Dynamic Pairs Trading Strategy For The Companies Listed In The Istanbul Stock Exchange
No full textIn this research we performed pairs trading strategy based on a comparative mean reversion of asset prices with daily data over the period 2002 through 2008 in Istanbul Stock Exchange. We did not categorize stock pairs by sectors and therefore it is possible to observe mean reversion characteristics of different stocks that are selected from ISE-30 index. The initial formation period is 125 days (approx. 6 months) while we measure the performance results daily. Then both formation process and trading strategies have been structured as dynamic (rolling windows) market trading model through 2008. The results indicate that pairs produced average returns of % 3.36 daily comparing with the naïve buy and hold strategy. However ISE30 daily average return performance % 0.038 between 2002-2008 period. Our trading constraints and trading commissions take away the excess return on pairs mostly. Furthermore, the performance analysis reveals that the pairs trading strategy yields excess returns with less volatility than the market portfolio.mean reversion, pairs trading, distance method, market neutral portfolio, Istanbul Stock Exchange, trading strategies
Financial globalization: a description from the standpoint of a process approach = Фінансова глобалізація: характеристика з позицій процесного підходу
No full textOnyshchenko S.V. Financial globalization: a description from the standpoint of a process approach // Information Technologies and Management 2017 : theses of the 15th International Scientific Conference, April 27-28. – Riga : ISMA University, 2017. – P. 140-141.The complexity of the financial globalization process is caused not only by the presence of a significant number of subprocesses, their scale, and depth of consequences but also common consequences of these subprocesses, for which a synergistic effect is observed. Author proved that manifestation of financial globalization caused by the growth of financial markets and the priority development of the international financial sector in comparison with the real sector of the world economy.
The descriptive model of financial globalization from the position of process approach is proposed, taking into account the subjects and objects of financial globalization.Складність процесу фінансової глобалізації зумовлена не лише наявністю значної кількості підпроцесів, їх масштаб і глибину наслідків, а також спільні наслідки цих підпроцесів, для яких спостерігається синергетичний ефект.
Автором доведено, що прояв фінансової глобалізації зумовлений зростанням фінансових ринків та пріоритетним розвитком
міжнародний фінансовий сектор у порівнянні з реальним сектором світової економіки.
Запропоновано описову модель фінансової глобалізації з позиції процесного підходу з урахуванням суб’єктів та об’єктів фінансової глобалізації
Numerical simulation of impact noise generated at the railway insulated joint
No full textThis paper presents a full finite element (FE) model of wheel-track interaction to study the wheel-rail impact noise excited by an insulated joint (IJ). The integration is performed in the time domain with an explicit central difference scheme. The vibratory behaviour of the track and wheel model are respectively validated with hammer test and Axle Box Acceleration (ABA) measurement. By making use of the calculated velocities and pressures on the vibrating surfaces, the boundary element method (BEM) based on Helmholtz equation is adopted to transform the vibrations of the wheel-track into acoustic signals. The decay rate of impact noise at different frequency bands during propagation are analysed. The predictions of total impact noise radiation and the noise contributions of different track components are in good agreement with results reported in the literature, while the effective frequency range is successfully extended from 5 kHz to 10 kHz.Accepted Author ManuscriptRailway Engineerin
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