Abstract

The persistent depletion of fossil fuels has encouraged mankind to look for alternatives fuels that are renewable and environment-friendly. One of the promising and renewable alternatives to fossil fuels is bio-diesel produced by means of the batch transesterification process. Control of the batch transesterification process is difficult due to its complex and non-linear dynamics. It is expected that some of these challenges can be addressed by developing control strategies that directly interact with the process and learning from the experiences. To achieve the same, this study explores the feasibility of reinforcement learning (RL) based control of the batch transesterification process. In particular, the present study exploits the application of twin delayed deep deterministic policy gradient (TD3) based RL for the continuous control of the batch transesterification process. These results showcase that TD3 based controller is able to control batch transesterification process and can be a promising direction towards the goal of artificial intelligence-based control in process industries.

Abstract

The design, simulation, analysis, and measurement results of a spark gap switched dipole antenna with a pulse repetition frequency (PRF) of 100 Hz when excited with a double exponential pulse are reported. The spark gap is filled with hydrogen owing to its superior recovery rate. The theoretical analysis of such an antenna is also presented and the results obtained closely match the measured values. When a voltage of 144 kV p-p is input to the antenna, a peak radiated field of 20.4 kV/m was observed at 10 m. The corresponding figure of merit (FoM) of the proposed antenna computes to 1.42 which is higher than those in the literature.

Abstract

The paper presents a sub-nW BJT based temperature sensor for ultra-low power microsystems. The sensor is based on amplifying the difference between base-emitter voltages of BJTs using gate-leakage transistors. Implemented in UMC 65nm technology, the sensor occupies an area of 0.005mm 2 . It achieves a maximum non-linearity error of 0.12°C(3σ) over the temperature range of –55°C to 80°C. Without any trimming, a worst case inaccuracy of +0.36°C/ –1.61°C is observed w.r.t process variations, depicting the process-invariant nature of the temperature sensor. It also achieves a low supply sensitivity of 0.56°C/V over a wide supply range of 0.7V-3V. The power consumption of the sensor is 419pW at 27°C and 0.7V supply.

Abstract

With the rise in state-of-the-art communication modes for vehicles such as vehicle to vehicle (V2V), vehicle to infrastructure (V2I) and vehicle to cloud (V2C), modern vehicles are increasingly being connected to cloud and fog/edge nodes. These vehicle connectivity modes have enabled the realization of Vehicular Edge Computing (VEC) paradigm, whereby vehicles can leverage fog/edge node resources for storage/computation. In a VEC system, vehicles receive very important and large quantity of data from edge nodes, which is termed as data delivery. In addition, edge nodes can execute some services and send the results back to the vehicle, which is called service delivery. Fast and efficient edge resource allocation for data/service delivery is important in order to serve as many vehicles as possible in the VEC system. However, edge resource allocation is complex with large number of edges and vehicles, while also considering vehicle flow parameters. In this work, we propose Edge-Pairwise Optimal Data/Service Delivery (E-PODS), which is a fast and efficient heuristic for data/service delivery. Through experiments with synthetic and real vehicular traces, we demonstrate that E-PODS is considerably faster than the optimal approach, while making resource allocations that are close to optimal in terms of total edge bandwidth cost and number of serviced vehicles.

Abstract

The performance of replication-based distributed databases is affected due to non-uniform storage across storage nodes (also called data skew) and reduction in the replication factor during operation, particularly due to node additions or removals. Data rebalancing refers to the communication involved between the nodes in correcting this data skew, while maintaining the replication factor. For carefully designed distributed databases, transmitting coded symbols during the rebalancing phase has been recently shown to reduce the communication load of rebalancing. In this work, we look at balanced distributed databases with random placement, in which each data segment is stored in a random subset of r nodes in the system, where r refers to the replication factor of the distributed database. We call these as decentralized databases. For a natural class of such decentralized databases, we propose rebalancing schemes for correcting data skew and the reduction in the replication factor arising due to a single node addition or removal. We give converse arguments which show that our proposed rebalancing schemes are optimal asymptotically in the size of the file.Due to space restrictions, the full version of this paper, containing proofs and additional results, is made available in [1].

Abstract

The problem of data exchange between multiple nodes with (not necessarily uniform) storage and communication capabilities models several current multi-user communication problems like Coded Caching, Data shuffling, Coded Computing, etc. The goal in such problems is to design communication schemes which accomplish the desired data exchange between the nodes with the optimal (minimum) amount of communication load. In this work, we present a converse to such a general data exchange problem between multiple nodes. The expression of the converse depends only on the number of bits to be moved between different subsets of nodes, and does not assume anything further specific about the parameters in the problem. Specific problem formulations, such as those in Coded Caching, Coded Data Shuffling, Coded Distributed Computing, and some of their variants, naturally can be seen as instances of this generic data exchange problem. Applying our generic converse to such problems, we recover known important converses for these settings and some of their variants in a simpler way. Further, for a generic coded caching problem with multiple transmitters, receivers and cache sizes, we show a new general converse which subsumes many existing results. We also employ our bound to obtain a new tight converse bound for the multi-node removal case in the Coded Data Rebalancing problem, in which nodes must exchange information to ‘rebalance’ a storage cluster after some node failures occur.Due to space restrictions, the full version of this paper, containing proofs and additional results, is made available in [1].

Abstract

We consider the centralized coded caching system where a library of files is available at the server and their subfiles are cached at the clients as prescribed by a placement delivery array (PDA). We are interested in the problem where a specific file in the library is replaced with a new file at the server, the contents of which are correlated with the file being replaced, and this replacement needs to be communicated to the caches. The server loses the original file when the replacement is done and is unaware of the differences between the two files, whereas each cache has access to specific subfiles of the original file as dictated by the PDA. We model the correlation between the two files by assuming that they differ in at the most  subfiles, and aim to reduce the number of bits broadcast by the server to update the caches. We design a new elegant coded transmission strategy for the server to update the caches blindly, and also identify another simple scheme that is based on MDS codes. We then derive converse bounds on the minimum cost ` among all linear strategies. For two well-known families of PDAs – the MaddahAli-Niesen scheme and a scheme by Tang & Ramamoorthy and Yan et al. – we show that our new scheme has cost `when the updates are sufficiently sparse, while the scheme using MDS codes has order-optimal cost when the updates are dense.

Abstract

In the pliable index coding (PICOD) problem, a server is to serve multiple clients, each of which possesses a unique subset of the complete message set as side information and requests a new message which it does not have. The goal of the server is to do this using as few transmissions as possible. This work presents a hypergraph coloring approach to the PICOD problem. A textit{conflict-free coloring} of a hypergraph is known from literature as an assignment of colors to its vertices so that each edge of the graph contains one uniquely colored vertex. For a given PICOD problem represented by a hypergraph consisting of messages as vertices and request-sets as edges, we present achievable PICOD schemes using conflict-free colorings of the PICOD hypergraph. Various graph theoretic parameters arising out of such colorings (and some new variants) then give a number of upper bounds on the optimal PICOD length, which we study in this work. Our achievable schemes based on hypergraph coloring include scalar as well as vector linear PICOD schemes. For the scalar case, using the correspondence with conflict-free coloring, we show the existence of an achievable scheme which has length where refers to a parameter of the hypergraph that captures the maximum `incidence' number of other edges on any edge. This result improves upon known achievability results in PICOD literature, in some parameter regimes.

Abstract

Vehicular Ad Hoc Network (VANET) and Internet of Vehicle (IoV) technologies are particularly attracting attention from industry communities because of the intelligent transportation systems of smart city technologies. This study proposes an authentication and key agreement protocol for vehicle-to-vehicle(V2V) communication of IoV. Through V2V communication, traffic system management and road safety can be guaranteed. However, V2V communication cannot manage many vehicles as a whole, so it needs to be segmented and communicated by region. Therefore, considering locality, key agreement is made for V2V communication of the same or different regions, and a lightweight protocol is proposed for dynamic properties of vehicles to achieve such a goal. In addition, since the vehicle information is transmitted through a public channel, the security against various attacks is guaranteed by using mutual authentication and honey_list technology. It provides verification of safety through a detailed security analysis using the formal analysis using the widely-accepted Real-Or-Random(ROR) model, formal security verification using the broadly-accepted Automated Validation of Internet Security Protocols and Applications(AVISPA) software validation tool and non-mathematical(informal) security analysis. In addition, a detailed comparative study that the proposed scheme can be applied in the communication environment between actual vehicles as compared to other existing competing schemes.

Abstract

In recent years, the Internet of things (IoT) has become an encouraging communication paradigm that has numerous applications including smart city, smart home and intelligent transportation system. The information sensed by several IoT smart devices can be security stored at the (cloud) servers. An external user, being a client, can access the services from a server for the sensing information, provided that a mutual authentication happens among them. Using the established session key among the user and the server, encrypted information with the help of session key can be delivered to the user by the server securely. Recently, Rana et al. proposed a smart-card based remote user authentication scheme using user password. In this comment paper, we carefully analyzed the scheme of Rana et al. and tracked down that their scheme is insecure against serious attacks, including stolen smart card attack, privileged-insider attack, user impersonation attack, password change attack and Ephemeral Secret Leakage (ESL) attack. Furthermore, their scheme does not preserve untraceability feature. To remedy these security pitfalls, we also provide some remedies that can help in building more secure and effective user authentication scheme to apply in securing next generation IoT infrastructure.