Design and development of energy efficient solar tunnel dryer for industrial drying

A natural convection poly house walk-in type solar tunnel dryer was designed and used for drying surgical cotton on industrial scale. This article deals with the basic design criterion used for development of solar tunnel dryer and result of drying of surgical cotton in actual use. A batch of surgical cotton of 600 kg by mass, having an initial moisture content of 40% wet basis from which 210 kg of water is required to be removed to get a desired moisture content of about 5% wet basis, is used as the drying load in designing the dryer. A drying time of 7–8 h is assumed for the anticipated test location (Udaipur, 27° 42′ N, 75° 33′ E) with an expected average solar irradiance of 5.5 kW m⁻². Average cost of drying one batch of surgical cotton in a solar tunnel dryer has been worked out to be approximately 4.63 USD as compared to 30.00 USD in the existing diesel fired dryer.     

Dynamic attribute based vehicle authentication

Modern vehicles are proficient in establishing a spontaneous connection over a wireless radio channel, synchronizing actions and information. Security infrastructure is most important in such a sensitive scope of vehicle communication for coordinating actions and avoiding accidents on the road. One of the first security issues that need to be established is authentication via IEEE 1609.2 security infrastructure. According to our preliminary work, vehicle owners are bound to preprocess a certificate from the certificate authority. The certificate carries vehicle static attributes (e.g., licence number, brand and color) certified together with the vehicle public key in a monolithic manner. Nevertheless, a malicious vehicle might clone the static attributes to impersonate a specific vehicle. Therefore, in this paper we consider a resource expensive attack scenario involving multiple malicious vehicles with identical visual static attributes. Apparently, dynamic attributes (e.g., location and direction) can uniquely define a vehicle and can be utilized to resolve the true identity of the vehicle. However, unlike static attributes, dynamic attributes cannot be signed by a trusted authority beforehand. We propose an approach to verify the coupling between non-certified dynamic attributes and certified static attributes on an auxiliary communication channel, for example, a modulated laser beam. Furthermore, we illustrate that the proposed approach can be used to facilitate the usage of existing authentication protocols such as NAXOS, in the new scope of ad-hoc vehicle networks. We use BAN logic to verify the security claims of the protocol against the passive and active interception.     

Study of Non-lubricated Wear of the Al–Si Alloy Composite Reinforced with Different Ratios of Coarse and Fine Size Zircon Sand Particles at Different Ambient Temperatures

In the present work, a detailed study of ceramic reinforcement of different size ranges in the matrix of LM13 alloy on the friction and wear behavior has been carried out. For this purpose, LM13/Zr composite containing 10 wt% zircon sand particles of different size ranges using stir casting process has been developed. Zircon sand particles were incorporated in two ways: firstly as single size reinforcement and secondly dual size reinforcement. Durability of the composites was tested by finding the wear rate of the composite against the steel disk by pin-on-disk method. Addition of zircon sand particles in the LM13 alloy improves the hardness of the composite as well as wear resistance. Wear rate of the developed composites was tested under different test conditions by varying the applied load and ambient temperatures. Wear rate of the composite changes significantly at different ambient temperatures. SEM analysis of the worn surfaces was done to know the operative wear mechanism.     

On minimizing end-to-end delay with optimal traffic partitioning

Multipath transport provides higher usable bandwidth for a session. It has also been shown to provide load balancing and error resilience for end-to-end multimedia sessions. Two key issues in the use of multiple paths are 1) how to minimize the end-to-end delay, which now includes the delay along the paths and the resequencing delay at the receiver, and 2) how to select paths. This paper presents an analytical framework for the optimal partitioning of real-time multimedia traffic that minimizes the total end-to-end delay. Specifically, it formulates optimal traffic partitioning as a constrained optimization problem using deterministic network calculus and derives its closed-form solution. Compared with previous work, the proposed scheme is simpler to implement and enforce. This analysis also greatly simplifies the solution to the path selection problem as compared to previous efforts. Analytical results show that for a given flow and a set of paths, a minimal subset can be chosen to achieve the minimum end-to-end delay with O(N) time, where N is the number of available paths. The selected path set is optimal in the sense that adding any rejected path to the set will only increase the end-to-end delay.     

MRTP: a multiflow real-time transport protocol for ad hoc networks

Real-time multimedia transport has stringent quality of service requirements, which are generally not supported by current network architectures. In emerging mobile ad hoc networks, frequent topology changes and link failures cause severe packet losses, which degrade the quality of received media. However, in such mesh networks, there usually exist multiple paths between any source and destination nodes. Such path diversity has been demonstrated to be effective in combating congestion and link failures for improved media quality. In this paper, we present a new protocol to facilitate multipath transport of real-time multimedia data. The proposed protocol, the multiflow real-time transport protocol (MRTP), provides a convenient vehicle for real-time applications to partition and transmit data using multiple flows. We demonstrate through analysis that data partitioning, which is an essential function of MRTP, can effectively reduce the short-range dependence of multimedia data, thus improving its queueing performance in underlying networks. Furthermore, we show that a few flows are sufficient for MRTP to exploit most of the benefits of multipath transport. Finally, we present a comprehensive simulation study on the performance of MRTP under a mobile ad hoc network. We show that with one additional path, MRTP outperformed single-flow RTP by a significant margin.     

CoopMAC: A Cooperative MAC for Wireless LANs

Due to the broadcast nature of wireless signals, a wireless transmission intended for a particular destination station can be overheard by other neighboring stations. A focus of recent research activities in cooperative communications is to achieve spatial diversity gains by requiring these neighboring stations to retransmit the overheard information to the final destination. In this paper we demonstrate that such cooperation among stations in a wireless LAN (WLAN) can achieve both higher throughput and lower interference. We present the design for a medium access control protocol called CoopMAC, in which high data rate stations assist low data rate stations in their transmission by forwarding their traffic. In our proposed protocol, using the overheard transmissions, each low data rate node maintains a table, called a CoopTable, of potential helper nodes that can assist in its transmissions. During transmission, each low data rate node selects either direct transmission or transmission through a helper node in order to minimize the total transmission time. Using analysis, simulation and testbed experimentation, we quantify the increase in the total network throughput, and the reduction in delay, if such cooperative transmissions are utilized. The CoopMAC protocol is simple and backward compatible with the legacy 802.11 system. In this paper, we also demonstrate a reduction in the signal-to-interference ratio in a dense deployment of 802.11 access points, which in some cases is a more important consequence of cooperation     

Facile Preparation of Multifunctional WS2/WOx Nanodots for Chelator‐Free 89Zr‐Labeling and In Vivo PET Imaging

While position emission tomography (PET) is an important molecular imaging technique for both preclinical research and clinical disease diagnosis/prognosis, chelator‐free radiolabeling has emerged as a promising alternative approach to label biomolecules or nanoprobes in a facile way. Herein, starting from bottom‐up synthesized WS₂ nanoflakes, this study fabricates a unique type of WS₂/WO_x nanodots, which can function as inherent hard oxygen donor for stable radiolabeling with Zirconium‐89 isotope (⁸⁹Zr). Upon simply mixing, ⁸⁹Zr can be anchored on the surface of polyethylene glycol (PEG) modified WS₂/WO_x (WS₂/WO_x‐PEG) nanodots via a chelator‐free method with surprisingly high labeling yield and great stability. A higher degree of oxidation in the WS₂/WO_x‐PEG sample (WS₂/WO_x (0.4)) produces more electron pairs, which would be beneficial for chelator‐free labeling of ⁸⁹Zr with higher yields, suggesting the importance of surface chemistry and particle composition to the efficiency of chelator‐free radiolabeling. Such ⁸⁹Zr‐WS₂/WO_x (0.4)‐PEG nanodots are found to be an excellent PET contrast agent for in vivo imaging of tumors upon intravenous administration, or mapping of draining lymph nodes after local injection.