Showing papers by "Yaşar University published in 2017"

A Simple and Compact Algorithm for SIDH with Arbitrary Degree Isogenies

Abstract: We derive a new formula for computing arbitrary odd-degree isogenies between elliptic curves in Montgomery form. The formula lends itself to a simple and compact algorithm that can efficiently compute any low odd-degree isogenies inside the supersingular isogeny Diffie-Hellman (SIDH) key exchange protocol. Our implementation of this algorithm shows that, beyond the commonly used 3-isogenies, there is a moderate degradation in relative performance of \((2d+1)\)-isogenies as d grows, but that larger values of d can now be used in practical SIDH implementations.

Smart vehicle monitoring and assistance using cloud computing in vehicular Ad Hoc networks

Abstract: The increasing number of on road vehicles has become a major cause for congestion, accidents and pollution. Intelligent Transportation Systems (ITS) might be the key to achieve solutions that help in reducing these problems significantly. The connected vehicular networks stream is a rapidly growing field for research and development of various real-time applications. In this paper, novel techniques have been proposed to serve the speed based lane changing, collision avoidance and time of arrival (TOA) based localization in Vehicular Ad Hoc Networks (VANETs). As GPS requires clear line-of-sight for accurate services of positioning and localization applications, we designed a Time of Arrival (ToA) based algorithm for areas where strong GPS signals are unavailable. Collision avoidance using automatic braking and camera-based surveillance are a few other applications that we addressed. The feasibility and the viability of the algorithms were demonstrated through simulations in Simulation of Urban Mobility (SUMO) and Network Simulator-2 (NS-2). We prototyped a working hardware and tested it on actual vehicles to assess the effectiveness of the proposed system. We designed a mobile app interface for the on-board unit for smart, efficient and remote traffic monitoring. The integrated VANET Cloud Computing architecture acts as the platform for the proposed applications.

Graph-based solution for performance evaluation of shuttle-based storage and retrieval system

Abstract: The aim of this study is to provide a graph-based solution for performance evaluation of a new autonomous vehicle-based storage and retrieval system, shuttle-based storage and retrieval system (SBS/RS), under various design concepts. By the graph-based solution, it is aimed the decision-maker (i.e. warehouse manager) evaluates a pre-defined system’s performance promptly and decides on the correct design concept based on his/her requirements from thousands of alternative design scenarios of SBS/RS. The design concepts include number of bays (NoB), aisles (NoA) and tiers (NoT) for the rack design and arrival rate of storage/retrieval (S/R) transactions to an aisle of the warehouse (AR). The performance of the system is evaluated in terms of average utilisation of lifts and average cycle time of S/R transactions. Simulation is utilised for the modelling purpose. Seven NoT, seven NoB and six AR scenarios are considered in the experiments. Hence, 294 experiments are completed to obtain the graphs. By this stud...

Understanding the links among innovation performance, market performance and financial performance

Abstract: Innovation and its impacts on business performance are strategically vital deliberations for modern business organizations In this study, we examine how innovation performance affects two different facets of firm performance: market performance and financial performance Many studies address the relationship between innovation and business performance, but few empirical studies analyze the interplay between those variables Research results reveal a suppression effect of market performance on the innovation–financial performance relationship We find a negative direct relationship between innovation and financial performance; however, market performance reverses this negative effect to a positive total influence through its suppression effect This result indicates the vital role of market performance in converting innovation to positive financial outcomes The proposed mediation model is relevant regardless of the set of firm-level and environmental contingency variables

An online structurally constrained LQR design for damping oscillations in power system networks

Abstract: This paper presents an online distributed control design for suppressing inter-area oscillations in large power systems under structural constraints posed on the underlying communication network. The presence of multiple clusters of generators in a power system results in several inter-area oscillation modes. By modal analysis, we first show that the contribution of each inter-area mode on the electromechanical state response of the generators is heavily dependent on the perturbed initial state of the system. We then take advantage of this observation to design structural constraints on the communication graph. A parallelized constrained linear quadratic regulator (LQR) design is then proposed to balance the tradeoff between performance and the level of sparsity induced in the network. Algorithms for practical implementation of the design are provided. Results are compared with the full order LQR, and illustrated on the New England 39-bus power system model.

How to (Pre-)Compute a Ladder

Abstract: In the RFC 7748 memorandum, the Internet Research Task Force specified a Montgomery-ladder scalar multiplication function based on two recently adopted elliptic curves, “curve25519” and “curve448”. The purpose of this function is to support the Diffie-Hellman key exchange algorithm that will be included in the forthcoming version of the Transport Layer Security cryptographic protocol. In this paper, we describe a ladder variant that permits to accelerate the fixed-point multiplication function inherent to the Diffie-Hellman key pair generation phase. Our proposal combines a right-to-left version of the Montgomery ladder along with the pre-computation of constant values directly derived from the base-point and its multiples. To our knowledge, this is the first proposal of a Montgomery ladder procedure for prime elliptic curves that admits the extensive use of pre-computation. In exchange of very modest memory resources and a small extra programming effort, the proposed ladder obtains significant speedups for software implementations. Moreover, our proposal fully complies with the RFC 7748 specification. A software implementation of the X25519 and X448 functions using our pre-computable ladder yields an acceleration factor of roughly 1.20, and 1.25 when implemented on the Haswell and the Skylake micro-architectures, respectively.

A multi-objective model for multi-production and multi-echelon closed-loop pharmaceutical supply chain considering quality concepts: NSGAII approach

Abstract: Quality of medical and pharmaceutical products has a key role in healthcare systems such as hospitals for better services to patients. This study proposes a comprehensive multi-objective mathematical model in healthcare supply chain considering quality and green concepts. The proposed model includes three objective functions. The first minimizes total manufacturing costs including transportation; purchasing maintenance, deterioration, setup, recycling, collecting and disposal costs. The second maximizes quality level of production. The third minimizes environmental effects of the products and transportations. The proposed model is complicated because of its nature and listed in the NP-hard. Hence, we use NSGAII approach for solving this model. The numerical example illustrates steps of the solution method. The solution representation for 4 suppliers, 2 recycling centers and 3 productions shows for supplier 1 (1100, 600, 1000) and supplier 2 (1000, 900, 400), recycling center 2 has a good performance and for supplier 3 (700, 500, 800) and supplier 4 (400, 950, 0), recycling center 1 has a good performance. Then, we need to improve the performance of the rest recycling centers per supplier. To measure the capabilities of multi-objective meta-heuristics, we used Number of Pareto solutions, spacing metric and quality metric criteria. Finally, the results show that the proposed algorithm has high quality to solve the model.

Demographic differences on service quality and perceived value in private online shopping clubs

Abstract: The objective of this study was to investigate the differences of demographic variables on e-service quality and perceived value in private online shopping clubs. How demographics differ in service quality and perceived value in private online shopping club was the research question, and the hypotheses were developed based on this question. The questionnaire contained three parts as the questions regarding online shopping behavior, demographic questions, and the constructs of E-S-QUAL, and perceived value. The survey was administered to a random sample of 280 college students by the technique of face-to-face survey. Findings showed that there was no significant gender difference on e-service quality and perceived value, however age and the length of private online shopping had significant differences on e-service quality and perceived value. Income level had no significant difference on e-service quality whereas it had a significant difference on perceived value. This study was unique and original...

Jacobian Coordinates on Genus 2 Curves

Abstract: This paper presents a new projective coordinate system and new explicit algorithms which together boost the speed of arithmetic in the divisor class group of genus 2 curves. The proposed formulas generalize the use of Jacobian coordinates on elliptic curves, and their application improves the speed of performing cryptographic scalar multiplications in Jacobians of genus 2 curves over prime fields by an approximate factor of 1.25x. For example, on a single core of an Intel Core i7-3770 (Ivy Bridge), we show that replacing the previous best formulas with our new set improves the cost of generic scalar multiplications from 239,000 to 192,000 cycles and drops the cost of specialized GLV-style scalar multiplications from 155,000 to 123,000 cycles.

An analysis of Emergency Medical Services demand: Time of day, day of the week, and location in the city

Abstract: Objective Effective planning of Emergency Medical Services (EMS), which is highly dependent on the analysis of past data trends, is important in reducing response time. Thus, we aimed to analyze demand for these services based on time and location trends to inform planning for an effective EMS. Materials and methods Data for this retrospective study were obtained from the Izmir EMS 112 system. All calls reaching these services during first six months of 2013 were descriptively analyzed, based on time and location trends as a heat-map form. Results The analyses showed that demand for EMS varied within different time periods of day, and according to day of the week. For the night period, demand was higher at the weekend compared to weekdays, whereas for daytime hours, demand was higher during the week. For weekdays, a statistically significant relation was observed between the call distribution of morning and evening periods. It was also observed that the percentage of demand changed according to location. Among 30 locations, the five most frequent destinations for ambulances, which are also correlated with high population densities, accounted for 55.66% of the total. Conclusion The results of this study shed valuable light on the areas of call center planning and optimal ambulance locations of Izmir, which can also be served as an archetype for other cities.

Quality function deployment application for improving quality of education in business schools

Abstract: There is an increasing competition between universities globally to attract students. At this point, to compete, it is imperative for the universities to improve the quality of education provided for their stakeholders, including students, parents, and employers. For improving the quality of education, first of all, the universities should make efforts to understand stakeholder expectations, by analyzing their needs and wants. For this purpose, the authors incorporated the quality function deployment technique with fuzzy analytical network process. Due to the vagueness present in the evaluation of relative importance of the criteria for higher education, fuzzy set theory is integrated.

Numerical analysis of a near-room-temperature magnetic cooling system

Abstract: In this study, for a near-room-temperature magnetic cooling system, a decoupled multi-physics numerical approach (Magnetism, Fluid Flow, and Heat Transfer) is developed using a commercial CFD solver, ANSYS-FLUENT, as a design tool. User defined functions are incorporated into the software in order to take into account the magnetocaloric effect. Magnetic flux density is assumed to be linear during the magnetization and demagnetization processes. Furthermore, the minimum and maximum magnetic flux densities (Bmin and Bmax) are defined as 0.27 and 0.98, respectively. Two different sets of analyses are conducted by assuming an insulated cold heat exchanger (CHEX) and by defining an artificial cooling load in the CHEX. As a validation case, experimental work from the literature is reproduced numerically, and the results show that the current methodology is fairly accurate. Moreover, parametric analyses are conducted to investigate the effect of the velocity of heat transfer fluid (HTF) and types of HTF on the performance of the magnetic cooling system. Also, the performance metrics of the magnetic cooling system are investigated with regards to the temperature span of the magnetic cooling unit, and the cooling load. It is concluded that reducing the cycle duration ensures reaching lower temperature values. Similarly, reducing the velocity of the HTF allows reducing the outlet temperature of the HTF. In the current system, the highest temperature spans are obtained numerically as around 6 K, 5.2 K and 4.1 K for the cycle durations of 4.2 s, 6.2 s and 8.2 s, respectively.

An improvement on the Migrating Birds Optimization with a problem-specific neighboring function for the multi-objective task allocation problem

Abstract: Migrating Birds Optimization algorithm is improved for task allocation problem.A problem-specific neighboring function for task allocation problem is designed.To evaluate the solution quality, problem is solved by a quadratic programming tool.Performance of the algorithm is compared with 3 recent stochastic search algorithms. Allocating tasks to processors is a well-known NP-Hard problem in distributed computing systems. Due to the lack of practicable exact solutions, it has been attracted by the researchers working on heuristic-based suboptimal search algorithms. With the recent inclusion of multiple objectives such as minimizing the cost, maximizing the throughput and maximizing the reliability, the problem gets even more complex and an efficient approximate method becomes more valuable. In this work, I propose a new solution for the multi-objective task allocation problem. My solution consists in designing a problem-specific neighboring function for an existing metaheuristic algorithm that is proven to be successful in quadratic assignment problems. The neighboring function, namely greedy reassignment with maximum release (GR-MR), provides a dynamic mechanism to switch the preference of the search between the exploration and exploitation. The experiments validate both that the quality of the solutions are close to the optimal and the proposed method performs significantly better comparing to three other metaheuristic algorithms. Neighboring functions being the common reusable components of metaheuristic algorithms, GR-MR can also be utilized by other metaheuristic-based solutions in the future.