Efficient attribute-based signature and signcryption realizing expressive access structures

This paper addresses the open problem of designing attribute-based signature (ABS) schemes with constant number of bilinear pairing operations for signature verification or short signatures for more general policies posed by Gagné et al. in Pairing 2012. Designing constant-size ABS for expressive access structures is a challenging task. We design two key-policy ABS schemes with constant-size signature for expressive linear secret-sharing scheme (LSSS)-realizable monotone access structures. Both the schemes utilize only 3 pairing operations in signature verification process. The first scheme is small universe construction, while the second scheme supports large universes of attributes. The signing key is computed according to LSSS-realizable access structure over signer’s attributes, and the message is signed with an attribute set satisfying the access structure. Our ABS schemes provide the existential unforgeability in selective attribute set security model and preserve signer privacy. We also propose a new attribute-based signcryption (ABSC) scheme for LSSS-realizable access structures utilizing only 6 pairings and making the ciphertext size constant. Our scheme is significantly more efficient than existing ABSC schemes. While the secret key (signing key or decryption key) size increases by a factor of number of attributes used in the system, the number of pairing evaluations is reduced to constant. Our protocol achieves (a) ciphertext indistinguishability under adaptive chosen ciphertext attacks assuming the hardness of decisional Bilinear Diffie–Hellman Exponent problem and (b) existential unforgeability under adaptive chosen message attack assuming the hardness of computational Diffie–Hellman Exponent problem. The security proofs are in selective attribute set security model without using any random oracle heuristic. In addition, our ABSC achieves public verifiability of the ciphertext, enabling any party to verify the integrity and validity of the ciphertext.     

Peer-assisted adaptation in periodic broadcasting of videos for heterogeneous clients

The increasing use of streaming applications and wide variety of devices, such as handheld personal organizers, have raised new challenges, such as the provision of access to multimedia content for devices with limited computing and bandwidth capabilities. In this paper, we propose a technique for periodic broadcasting. Our technique allows clients with low bandwidth capability to be served in the same period as high-bandwidth clients, using peer-to-peer streaming between clients, and also works for clients with downstream capability below the video bit rate. In the proposed system, the server builds multicast trees of clients that allow clients with low bandwidth to be served by other clients with sufficient upstream bandwidth. Clients below the video bit rate will suffer additional, but only moderately noticeable, delays that occur as video is converted to lower quality. We performed extensive simulation and showed that our system can provide improved service performance for heterogeneous clients on periodic broadcasting protocols.     

Psychological effects of physical deficiencies in the residences on elderly persons: a case study in Trabzon Old Person's Home in Turkey

In this study, elderly persons' physical and spiritual necessities and their satisfaction in their residences are investigated by applying a comprehensive questionnaire on the residents of Trabzon Old Person's Home. By grouping the residents of the home according to their age, gender, marital status, occupation, health conditions, cultural status, and economic conditions, their expectations are determined. Physical conditions of the home are also examined in order to determine whether the necessities of the residents are met or not. The questionnaire consisting of 75 questions is applied to 60 people, and 4500 data points are analyzed by using SPSS software. In the results of this study, physical deficiencies that require elderly persons want to be in Trabzon Old Person's Home are determined. It is also determined that 86.7% of the residents are pleased with living in the old persons' home and they could get used to living in the old persons' home but 73.3% of the residents do not want to send someone in their family to the old person's home. These contradictory results show that residents do not want to live in old person's home but they adapt in there because of compulsoriness. This situation affects the residents' psychological well-being in a negative way.     

Empirical prediction limit estimation methods for feed-forward neural networks

Feed-forward neural networks (FFNs) have gained a lot of interest in the last decade as empirical models for their powerful representational capacity, non-parametric nature and multivariate characteristics. While these neural network models focus primarily on accurate prediction of output values, often outperforming their statistical counterparts in dealing with sparse date sets, they usually do not provide any information regarding the confidence with which they make these predictions. Since prediction limits (PLs) indicate the extent to which one can rely on predictions for making future decisions, it is of paramount importance to estimate these limits. Two empirical PL estimation methods for FFNs are presented. The two methods differ in one fundamental aspect: the method employed for modeling the properties of the neural network model residuals. While one method uses a local approximation scheme, the other utilizes a global approximation scheme. Simulation results reveal that both methods have their relative strengths and weaknesses.     

A semi-analytical model for the effective thermal conductivity of a multi-component polydisperse granular bed

A theoretical model to predict the effective thermal conductivity of a multi-component polydisperse granular bed is presented. A simple energy balance analysis is used to arrive at an approximate analytical expression for the effective thermal conductivity. Simulation of heat transfer in a granular bed is carried out using an open source Discrete Element Method (DEM) package called LIGGGHTS. The derived analytical expressions for the effective thermal conductivity compares well with the results obtained from DEM simulations for granular beds comprising of different components with different sizes.     

Design of Phosphide Anodes Harvesting Superior Sodium Storage: Progress,Challenges, and Perspectives

Sodium (Na) ion batteries (SIBs) are promising in stationary energy storage applications. Research is also afoot to seek suitable electroactive materials for use in SIBs. Recently, phosphides to be used in the anode for Na storage are particularly appealing due to their high specific capacities and low working potentials. The following matters are to deal with their inherent drawbacks of large volume variation and inferior interfacial stability upon Na insertion/extraction, which is believed to be largely responsible for capacity and cycling decay. Despite striking progress in addressing the above drawbacks, current studies on phosphides remain preliminary. In this review, an in-depth understanding of phosphides regarding Na storage mechanism, capacity assessment, phase change, and reaction types is provided. The effective strategies and the sound designs of phosphides for Na storage are also discussed. Their correlations between electrochemical behavior and chemical/structural characteristics are analyzed, in a bid to sort out the basic ideas for the design of high-performance phosphides that enable high-energy and durable SIBs. Doubtless, the experience and knowledge gained from the research on phosphides are shared, and the strategies are expected to extend the scope beyond phosphides.     

Modeling water resources under competing demands for sustainable development: A case study of Kaligandaki Gorge Hydropower Project in Nepal

The challenges posed by climate change require that the quantity and quality of water resources in Nepal be managed with sustainable development practices. The communities around the Kaligandaki Gorge Hydropower Project in the Myagdi District of Nepal depend on river flow for most of their rural and agricultural needs. Without a sustainable development plan, the growing population of the region, confined in an area with declining water resources, will face serious challenges to economic growth. Meteorological data show increasing annual average rainfall at a slight rate of about 0.284 mm/year, with erratic annual percentage change in rainfall in the area. The mean and minimum temperatures show decreasing trends at the rates of 0.05℃ and 0.140 C per year, respectively. An assessment of the impacts on water availability for domestic and irrigation usage in the face of competing demands caused by the hydropower development project in the Kaligandaki Gorge was undertaken. The water demand and supply modeling were conducted using the water evaluation and planning(WEAP) model, based on discharge data from the Kaligandaki River, which were obtained from the Department of Hydrology and Meteorology, Nepal. The available data from 2001 to 2003 were used to estimate the model parameters while the stability of these parameters was tested with a validation period from2004 to 2007. The performance of the model was assessed through statistical measures of calibration with the root mean square error and coefficient of determination, whose values were 0.046% and 0.79, respectively. Two scenarios were created in addition to the base case scenario:the discharge decrement scenario and new irrigation technology scenario. Analysis showed that a prioritization of demands will be necessary in the area in the near future for the purpose of sustainability of water resources, due to climate change impacts.     

‘Worksome but Rewarding’ –Stakeholder Perceptions on Value in Collaborative Design Work

In this paper, we examine collaborative design projects in school contexts with many different stakeholders. We look at the value created for and by different stakeholders, focusing on value as a benefit, which is experienced – perceived and determined – by the beneficiaries themselves in the value co-creation process. As our focus is in “value-in-use”, i.e., value which emerges through activities taking place in a specific space, time, and context, we define value through subjective experience of people involved. We apply in our study the concept of value co-creation, where value is understood emerging from collaborative activity between actors participating in the activity. We see that the value co-creation lens provides a useful means for the CSCW community to scrutinize and make sense of collaborative design projects. We categorized the perceived value for each stakeholder and discuss how these categories can help in gaining a deeper understanding of the value gained in collaborative design work as well as how value co-creation lens in more general can be used as a tool in collaborative design projects.     

Low Pressure Hexamethyldisiloxane (HMDSO)/Nitrogen Plasma Treatment on the Wettability and Surface Free Energy of Biaxial-Oriented Polypropylene (BOPP) Films

In this paper the influence of DC glow discharge HMDSO-N₂ plasma on wettability and surface properties of Biaxial-oriented polypropylene (BOPP) polymeric surfaces, has been investigated. The effects of plasma exposure time and HMDSO percent on the surface energy and wettability of the BOPP films were characterized using Fourier transform infrared spectroscopy (FTIR), Atomic force microscopy (AFM) and contact angle measurement. A clear change in the surface energy of BOPP films due to plasma treatment was observed. In this work we report changing surface properties of BOPP films instead of plasma treatment time and HMDSO ratios.     

Organic Geochemical Evaluations of Bituminous Rock and Coals in Miocene Himmetoglu Basin (Bolu, Turkey)

The studied area is a lake basin located in Bolu basin in Turkey. In the basin, from Upper Cretaceous to Upper Miocene 3,000-m thickness sediments were deposited. Upper Miocene Himmetoglu formation consisted of sandstone, claystone, and marl. To the middle level of the formation are located coal, bituminous limestone, and bituminous shales. In the basin, there are two coal beds whose thicknesses range from 1 to 13 m. The coals are easily breakable and black in color. In the coal beds exists some bituminous limestone and bituminous shales, and their thicknesses are between 5 and 45 cm. The amount of organic matter of the bituminous rocks from the Upper Miocene Himmetoglu formation are between 6.83 and 56.34 wt%, and the amount of organic matter of the bituminous limestone from the formation are between 13.58 and 57.16 wt%. These values indicate that these rocks have very good source potential. According to hydrogen index (HI), S₂/S₃, HI-T_max, and HI-OI (oxygen index) parameters, kerogen types of the bituminous rocks and coals belonging to Upper Miocene Himmetoglu formation are Type I, Type II, and Type III. In accordance with HI, S₂/S₃, HI-T_max, and HI-OI parameters, the bituminous rocks and coals from the Upper Miocene Himmetoglu formation are mostly immature.