277 research outputs found
Energy Minimization in Piperazine Promoted MDEA-Based CO2 Capture Process
No full textA piperazine (PZ)-promoted methyldiethanolamine (MDEA) solution for a carbon dioxide (CO2) removal process from the flue gas of a large-scale coal power plant has been simulated. An Aspen Plus® was used to perform the simulation process. Initially, the effects of MDEA/PZ concentration ratio and stripper pressure on the regeneration energy of CO2 capture process were investigated. The MDEA/PZ concentration ratio of 35/15 wt.% (35 wt. MDEA and 15 wt.% PZ) was selected as an appropriate concentration. The reboiler duty of 3.235 MJ/kg CO2 was obtained at 35/15 wt.% concentration ratio of MDEA/PZ. It was considered a reference or base case, and process modifications including rich vapor compression (RVC) process, cold solvent split (CSS), and the combination of both processes were investigated to check its effect on the energy requirement. A total equivalent work of 0.7 MJe/kg CO2 in the RVC and a reboiler duty of 2.78 MJ/kg CO2 was achieved in the CSS process. Similarly, the total equivalent work, reboiler duty, and condenser duty of 0.627 MJe/kg CO2, 2.44 MJ/kg CO2, and 0.33 MJ/kg CO2, respectively, were obtained in the combined process. The reboiler duty and the total equivalent work were reduced by about 24.6 and 16.2%, respectively, as compared to the reference case. The total energy cost saving was 1.79 M per year
On the spatial and temporal coherence of wireless vehicular short range channels
No full textWe consider spatial and temporal coherence of the vehicle–to–vehicle (V2V) wireless communication channel with focus on a suburban residential highway. The dominant reflectors in such an environment are vehicles passing in the adjacent lane and houses
along the road. Instead of treating the reflectors as point targets, the V2V short range propagation environment requires partitioning of the illuminated reflector side into
sufficiently small tiles. The channel transfer function is obtained as a superposition of specular reflections from the tiles, the line–of–sight (LOS) component, and the ground reflection. The tile size is selected to ensure that the ratio of the tile area to the tile–to–receiver distance satisfies the far field conditions. The reflected power is described by the tile radar cross section (RCS). The bistatic physical optics RCS model is adapted to account for the tile’s orientation with respect to the ray geometry. We apply the superposition model to the numerical analysis of two general scenarios
for a 22MHz channel in the 2.4GHz band. The first scenario considers a single vehicle reflector passing in the lane adjacent to the V2V communication pair. Both the vector network analyzer (VNA) experiments and the tiling model analysis illustrate that repositioning of the reflector, the transmitter, or the receiver by a few centimeters results in change of the signal power by several decibels. The second scenario analysis characterizes the channel coherence statistics for the
suburban residential highway. We consider the V2V single lane LOS and non–LOS geometries, where in the latter the receiver is shadowed by a large vehicle. The reflectors are both houses and vehicles passing in the opposite direction. The measure of channel coherence is the normalized spatial covariance calculated by correlating transfer functions corresponding to feasible receiver position pairs and performing spatial smoothing. The area of feasible receiver positions is divided into contiguous squares
whose size ensures wide sense quasi–stationarity within the square. Irrespective of direction the correlation remains high and a typical sedan roof usually does not provide sufficient spacing to obtain average inter–antenna correlation lower than 0.5. The upper bound on coherence time extends over the transmission time of multiple packets for systems in the considered band, and does not allow for usable time diversity.Ph.D.Includes bibliographical referencesIncludes vitaby Haris Krem
Towards More Flexible Models in High Dimensions
No full textThesis (Ph.D.)--University of Washington, 2018Recently, technological advances have allowed us to gather large and high-dimensional data. In high-dimensional data, the number of variables measured on each subject is quite large, often larger than the number of subjects. Consequently, there is growing need for improved supervised learning methods. We consider the setting in which we have an outcome variable and p covariates measured for n subjects; our goal is to estimate the conditional relationship between covariates and outcome. Fitting linear models to high-dimensional data has been extensively studied in the past two decades, and numerous methods have been proposed for this task, such as the lasso. On the other hand, more flexible or nonparametric modeling of high-dimensional data is relatively less studied. Desirable flexible models should be interpretable, computationally-efficient, and have theoretical guarantees. Existing literature fails to achieve these three properties simultaneously. In this dissertation, we extend the existing literature and address gaps within the literature. In Chapter 2, we present a general framework for fitting sparse interaction models. Our framework not only generalizes many existing methods, but allows us to build new estimators; we present two such novel estimators in Chapter 2. In Chapter 3, we develop a general framework for fitting sparse additive models; this framework encompasses state-of-the-art techniques for additive models. We develop an efficient algorithm for computation, and establish theoretical guarantees for our general framework. In Chapters 4 and 5, we develop two novel estimators for nonparametric regression and extend them to sparse additive models. The main appeal of these estimators is that the fitted models have a parsimonious representation; this facilitates interpretation of models. Using the general framework of Chapter 3, we derive efficient algorithms for the estimators of Chapters 4 and 5, and establish theoretical convergence rates
How does Cultural Diversity affect the management of warehouse staff
No full textBackground: In modern times it is undeniable that companies that foster diversity have been able to gain an edge over their competitors. Warehouses as every other workplace are trying to follow the trend of economic globalization and a study towards managing the diversity needs to be conducted in order to evaluate the processes that the managers within the warehouses use in order to integrate the workforce effectively. Method: This research uses a qualitative approach which involved semi structured interviews with 5 warehouses that operate within Jonkoping. The study is perceived through an interpretive research philosophy with an inductive research approach. Purpose: The purpose of this thesis is to investigate how cultural diversity is managed at the warehouses within Jonkoping. Also, a further research is conducted on how the tools and processes available to the managers working within the warehouse industry can help them foster diversity within their company. Conclusion: The results depict that the idea of having culturally diverse work teams is becoming increasingly popular and mangers working within the warehouse industry seem to take more interest in hiring people coming from different backgrounds. The major benefits of having a racially mixed team identified by managers were creativity and innovation. The major challenge that was brought up by managers was their ability to be responsive and adaptable towards the needs of their employees
Explosive indentation study of B4C-TiAlx composites fabricated by the dipping exothermic reaction process
No full textThe aim of this study is to fabricate a high volume fraction B4C-reinforced intermetallic matrix composite by the dipping exothermic reaction process and investigate the shock impact damage response of composites by explosive indentation experiment. It has been shown that the final microstructure of the dipping exothermic reaction process-fabricated composite can be tailored by treatment of the constituent powders and post heat treatment. The hardness and impact damage resistance of the fabricated composites were evaluated.This work is supported by grants (No. N62649-03-0007) from AROFE(US Army
Research Office Far-East). The author thanks Drs. J. W. McCauley of ARL, Sean Yu and
R. Olesinskiof AROFE
Increasing the Performance of Passive Communication with Ambient Light
No full textMost wireless communication technologies have been using the Radio Frequency (RF) spectrum for decades. Due to the popularity of the Internet of Things (IoT), the RF spectrum has started to become densely populated. Researchers have begun to explore other bands of the electromagnetic spectrum that can be utilized as a communication media. One of the promising choices is the visible light spectrum.Visible Light Communication (VLC) refers to the wireless communication technology that utilizes the visible light spectrum. This spectrum is thousands of times wider than the Radio Frequency (RF) spectrum and is license-free. In VLC, data is transmitted by turning a light source on and off. However, not every light source can be controlled. Passive light sources such as the sun provide an immense amount of light that can be used for wireless communication if we can develop ways to modulate them. One of the researches that use ambient light to create a wireless link is LuxLink. LuxLink uses liquid crystal shutters to control passive light sources and provides low energy, reliable, and flicker-free (safe) communication. This thesis addresses several problems that the current LuxLink system has.We present LuxLink+, an extension of LuxLink that provides two main improvements. Firstly, the data rate of the system is relatively low (80~bps). To increase the data rate, we provide a thorough analysis of the system’s bandwidth. Afterward, we modify the modulation technique, which increases the data rate to 1000~bps at a range of 1.5~m.Secondly, the system has a static data rate, which means that the system cannot adapt its data rate to changes in the environment. We implement a rate adaptation algorithm that can change its data rate accordingly. LuxLink+ improves the average throughput of the system by up to 85 percent compared to LuxLink.Electrical Engineering | Embedded System
Performance investigation of an integrated wind energy system for co-generation of power and hydrogen
No full textIn this paper, a wind turbine energy system is integrated with a hydrogen fuel cell and proton exchange membrane electrolyzer to provide electricity and heat to a community of households. Different cases for varying wind speeds are taken into consideration. Wind turbines meet the electricity demand when there is sufficient wind speed available. During high wind speeds, the excess electricity generated is supplied to the electrolyzer to produce hydrogen which is stored in a storage tank. It is later utilized in the fuel cell to provide electricity during periods of low wind speeds to overcome the shortage of electricity supply. The fuel cell operates during high demand conditions and provides electricity and heat for the residential application. The overall efficiency of the system is calculated at different wind speeds. The overall energy and exergy efficiencies at a wind speed 5 m/s are then found to be 20.2% and 21.2% respectively
Multigeneration system exergy analysis and thermal management of an industrial glassmaking process linked with a Cu–Cl cycle for hydrogen production
No full textA multigeneration system for hydrogen production linked with a glassmaking process via thermal management is examined in this study. The exhaust gas is interconnected with a Rankine cycle and the copper-chlorine (Cu–Cl) cycle for hydrogen production. The present system consists of a steam Rankine cycle, Cu–Cl cycle with multistage compression, double-stage organic Rankine cycle, and multi-effect desalination system. A Cu–Cl cycle based on the four-step model is employed with the proposed system. The useful system outputs are electricity, hydrogen, and fresh water. The simulation software packages utilized in the analysis and modeling are Engineering Equation Solver and Aspen Plus. The energy efficiency of the overall system is 36.5% while 38.1% is the exergy efficiency. The parametric studies are conducted to investigate the system performance. In addition, the effects of exhaust gas variables, such as flow rate, temperature, and pressure are examined to investigate the system performance
Civil war or genocide? : Britain and the secession of East Pakistan in 1971
No full text-- Acknowledgements -- Introduction : sovereignty, development and civil war / Aparna Sundar and Nandini Sundar -- Contextualizing civil wars in South Asia / Nandini Sundar -- Sri Lanka : military fiscalism and the politics of market reform at a time of civil war / Rajesh Venugopal -- The transnational political economy of civil war in Afghanistan / Alessandro Monsutti -- Aid and violence : development, insurgency and social transformation in Nepal / Antonio Donini and Jeevan Raj Sharma -- Civil war or genocide? : Britain and the secession of east Pakistan in 1971 / Anthony Dirk Moses -- The rise of jihadi militancy in Pakistan's tribal areas / Haris Gazdar, Yasser Kureshi and Asad Sayeed -- Routine emergencies : India's armed forces special powers act / Sanjib Baruah -- Local agitations in a globalized context : a case study of Shopian and Bomai / Gowhar Ashraf Fazili -- Articulating grievance in southeast Myanmar / Stephen Campbell -- About the editors and contributors -- Inde
The movement of harith b. surayj
No full textHAris bin Süreyc, uzun yıllar Emevîler'e hizmet etmiş bir kişi idi. Özellikle 110/729 yılında Beykend'de Türk güçlerine karşı yapılan savaşta askerleri cesaretlendiren kişilerden biri olarak hatırlanır. Daha sonra 116/734 yılında HAris bin Süreyc Horasan'da Emevî yönetimine karşı isyan etti. Fakat Horasan yöneticisi olan 'Asım b. Abdullah onu, Merv'de mağlup etti. O, Esed bin Abdullah el-Kasrî zamanında tekrar isyan etti. İkinci defa mağlup oldu. HAris bin Süreyc ve taraftarları Türgiş Hanı'na katıldı. Nasr bin SeyyAr Horasan yöneticisi olunca, Emevî halifesi Yezîd bin Velîd onu affetti. Böylece o, 127/745 yılında Merv'e geri döndü. Sonra Cuday el-KirmAnî ile birlikte Nasr bin SeyyAr'a karşı savaştılar. Ancak el-KirmAnî ile anlaşmadılar. Nihayetinde o, 128/746 yılında el-KirmAnî tarafından öldürüldü. HAris'in kAtibi olan Cehm bin SafvAn Mürcii idi. Bu yüzden o Mürcii mezhebinin bir üyesi olarak bilinir. Gerçekte ise; o, insanları Kuran ve Sünnete tabi olmaya çağıran dini bir ihyacıdır.Harith b. Surayj was a man who served for Umayyads in several years. Especially He is mentioned as one of courageous warriors in the battle against the forces of Turks at Baykand in 110/729. After Harith b. Surayj rebelled in Khurasan against Umayyad administration in 116/734. But Khurasan Administrator, 'Asım b. Abdillah defeated him at Marw. He rebelled again during Asad b.'Abdallah Al-Kasri. He was defeated twice. Harith b. Surayj with his adherents joined the Khakan of Turgesh. When was Nasr b. Sayyar Khurasan administrator, Umayyad Caliphate Yazid b. Valid pardoned him. Thus He came back to Marw in127/745. After Harith b. Surayj with Djuday al-Kirmani fougt against Nasr b. Sayyar. But He did not agree with al-Kirmani. Eventually he was killed by al-Kirmani in 128/746. Harith's secretary; Djahm b. Safwan was Murdji'i. For his reason he is mentioned as a member of this sect. In fact he was a religious revivalist who called upon people to follow the Quran and Sunnah
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