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Abstract:

Abstract:

Abstract:

Abstract:

Abstract:

Abstract: Consider a bottleneck in a road through which only one car can pass through. Suppose that at a time the car passing will have the most aggressive driver in queue and that the aggressiveness of an individual is measured by an attribute A ≡ Nτ σ where the quantity N varies randomly from person to person in the range 0 to 1, τ is the time for which the driver is waiting in the bottleneck and the parameter σ is the same for all individuals. Thus, we assume that the aggressiveness depends on the nature of the individual and increases with waiting time in a traffic jam. In support of the algebraic form of A, we show (numerically and analytically) that our hypothesis implies that the probability of waiting for a time τ will be P(τ ) ∝ τ α with the value of α fixed by σ. Empirical studies confirm such variation in P(τ ) with an exponent of 3.0 to 3.5 in two different cities of India and 1.5 for a traffic intersection in Germany. There is a possibility that the parameter σ (and hence α) is characteristic of a geographical region.

Abstract: Typically an Intelligent Transportation System (ITS) employs various types of infrastructure-based technologies into vehicles and roadways for monitoring traffic. But these solutions have high installation, maintenance, and operational costs. Further, most of these solutions are based on the assumptions of lane-based organized and homogeneous traffic, due to which these are ineffective in less organized traffic conditions which are common in developing countries. In this paper, we have proposed a cost-effective approach to infer the traffic state of the road by analyzing the cumulative acoustic signal collected from the microphone sensor of the user’s smartphone. To capture the distinctive characteristics of various traffic scenes, we explored two different types of features: Mel Frequency Cepstral Coefficients (MFCCs) and Wavelet Packet Transform (WPT). Based on the understanding of acoustic signals of different traffic scenes, various parameters of these features such as window size and MFCC dimensions are tuned for better detection accuracy and robustness. To validate the approach, field experiments were conducted in varied conditions on the roads of City X. Experimental results revealed that for binary traffic scene classification (‘busy-street’ vs. ‘quiet-street’), MFCC features are sufficient to get an overall accuracy of 100%. However, for ‘congestion’ vs. ‘medium-flow’ vs. ‘free-flow’ traffic scene classification, MFCC features yield a bit lower accuracy of 77.64%. In this scenario, it was observed that WPT features can be used to reduce the false positive rate, thereby providing an absolute gain of 11.38% in the classification accuracy over the MFCC baseline. Also, it has been observed that by crowdsourcing the traffic state information from multiple users’ smartphones, an effective accuracy improvement can be achieved for each traffic scene.

Abstract: Recent developments in wireless communication challenges microwave filters with more demanding requirements such as small size, light weight, high performance and low cost. Microstrip resonator have the higher performance than the conventional filtering technique for microwave devices. A triangular open loop resonator energized using electromagnetic (EM) and edge coupling is presented in this paper. Microstrip line is modified as a triangular open-loop resonator that introduces additional capacitance and inductance by re-orientation of electromagnetic field, there by selecting the operating frequencies. Depending on the type of coupling and position of the feed used the operating frequency of the filter changed for the same dimensions. EM and edge coupling is given to the resonator, when its gives band pass filters at 2.45 GHz and the effect of each coupling techniques are studied in detail. Better size reduction is observed for EM coupling than the edge coupling. The filters characteristics are analyzed in substrate FR4 epoxy by using ANSYS High Frequency Structure Simulator (HFSS) software. The design equations for the resonator predicts the frequency with less than 2% error with the simulated frequency. The optimized triangular open loop resonators are fabricated and validated using Keysight ENA 5080A Vector network Analyser. The simulated and measured of the resonator filter are comparable for center frequency, bandwidth, return loss and attenuation.

Abstract: A comparative study of the realization of 4 bit passive chipless resonator for RFID tag section using 4 resonators and 8 resonators is discussed in this paper. The designed 4 bit passive chipless RFID resonator tag can detect up to 15 objects. Basic resonator is a complementary spiral with direct coupling to the microstrip line (MSL), operating in the L band region. A 4 bit resonator structure using 4 complementary spirals and 8 complementary spirals are designed. The resonance obtained depends upon the length, width and gap of the spiral structure. The 4 bit resonator structure using 8 complementary spirals is twice the duplication of the 4 bit resonator using 4 complementary spirals. The operating frequencies of both the structures are almost the same. The 4 bit resonator structure using 8 complementary spirals gives the amplified version of the signal provided by 4 complementary spirals thus adding range and security to the system. Both the 4 bit spiral resonator structures were simulated using ANSYS HYSS 14. The optimized resonators are fabricated on FR4 substrate and simulated results are validated using Keysight E5080A ENA Vector Network Analyser.

Abstract: The cellular network range over the oceans is limited to about 15 km from the shore in most places. The service providers do not have any incentive to extend the coverage further. However, marine fishermen who routinely spend 5 to 7 days at the ocean on a single fishing trip are severely impacted by this. They go as far away as 120 km from the shore on some occasions and are completely cut off from the land during their fishing trips. Also, they are generally poor and need an economical solution to stay connected. We have developed and successfully prototyped an affordable solution based on a multilevel auto-reconfigurable backhaul infrastructure network. It uses long range (LR) Wi-Fi and extends the connectivity to 60 km and beyond over the oceans using heterogeneous networks and relay nodes. Multiple field trials involving up to four boats over the Arabian Sea have yielded consistent and repeatable results even under rough sea states. Additional experiments conducted over the backwaters by scaling up the network further have also yielded positive results. This work provides a detailed description of the architected solution and the results obtained.

Abstract: Artificially engineered materials, like metamaterials can be used to enhance the performance of devices. Split-ring resonators (SRRs) is the most widely used metamaterial at microwave regime. In this paper, edge coupled metamaterial filter using SRR with band stop characteristics in the frequency spectrum is proposed. Exhaustive simulations are conducted to understand the properties of the filter. The effects of the geometrical parameters on the resonance frequency are investigated. The proposed filter prototypes are tested using Vector Network Analyser and thus simulated results are validated.

Abstract: A coplanar waveguide (CPW) fed rectangular loop antenna with dual frequency characteristics applicable Wi-Fi bands is presented. The studies to calculate the dependency of frequencies on the antenna structure is carried out using ANSYS HFSS. From this, the antenna is optimized to have an enhanced gain of ˜ 8 dBi at 2.45 GHz and 3.83 dBi at 5.32 GHz. The radiation characteristics of the antenna are studied and the radiation pattern confirms the monopole characteristics at both the frequencies. The optimized antenna performance is confirmed by measurements using Vector Network Analyser. Since energized using coplanar waveguide the proposed antenna finds applications in Microwave Monolithic Integrated Circuits (MMIC) also.

Abstract: An antenna is an integral component in a wireless communication system. The choice of the antenna geometry of these systems depends on the preferred specifications. Depending upon the variation in the geometry and feeding technique, the performance of the antenna can be modified. For any communication system design an antenna with a better transmission range, improved reflection and radiation characteristics at the designed frequencies is desired. An asymmetric coplanar strip fed antenna is designed and analyzed in this paper. This structure gives better performance compared to microstrip and coplanar waveguide (CPW) fed omni-directional antennas. The proposed antenna is compact with reduced complexity, providing appreciable gain. A monopole antenna system with a metamaterial ground plane on the same plane is proposed. This antenna operates in the 2.45 GHz Wi-Fi band. The radiating element and the metamaterial ground plane are optimized for the best performance of the antenna system. For optimum performance of the antenna, open loop resonator is also studied as the ground plane. Miniaturization is achieved with metamaterial ground plane without changing the characteristic of the monopole antenna structure. The monopole antenna with the metamaterial ground plane is found to be compact with resonance at 2.45 GHz offering a 2 : 1 VSWR bandwidth of 217 MHz. The radiation pattern of the designed antenna is omni-directional with a gain of 3.124 dBi at the resonant frequency. The antenna is designed and optimized using ANSYS HFSS 14. The optimized antennas are fabricated using FR4 substrate and are experimentally validated using Vector Network Analyzer E5080A.

Abstract: In this paper a hybrid cavity substrate integrated waveguide filter is proposed and demonstrated for Ku band application. Hybrid cavity which is the combination of both circular and rectangular cavity, showcases a better frequency selectivity and Quality Factor in comparison with other cavity based substrate integrated waveguide filters. Quality Factor requirements are met by the introduction of shorting posts at specified points inside the cavity. Filter operates at a frequency of 13GHz with an optimized Q factor of 377.096.The detailed analysis of the proposed structure is simulated and studied using the ANSYS HFSS software.

Abstract: Present work proposes an Asymmetric Coplanar (ACPW) fed antenna providing wide band and omnidirectional radiation. Gain enhancement is achieved by the introducing perturbations on the shorted ground plane. The proposed antenna offers a 2 : 1 VSWR bandwidth of 741MHz at 5.2 GHz with the enhanced gain of 6.4 dBi. The parametric analysis and optimization of the antenna is done by using ANSYS HFSS. Optimized prototype is analyzed experimentally using Keysight E5080A Vector Network Analyzer. The proposed antenna will have wide range of applications in different wireless communication systems.

Abstract: For efficient monitoring and tracking of vehicles, aircraft or ships GPS (Global Positioning System) satellite based navigation system plays an inevitable role. For long range GPS communication and tracking, high gain antennas usually array antennas are preferred. Realized using butler matrix phased array antennas are potential candidate for providing long range communication providing directional beam. Butler matrix provides equal amplitude to the antennas by means of hybrid coupler, necessary beam orientation using phase shifter and ensures signal purity when transmission lines overlap by crossover circuit. Thus crossover will mitigate the GPS tracking of signal when transmission lines overlap each other maintaining high SNR. This paper focuses on the investigations of an L band planar crossover realised using microstrip technology. The crossover characteristics like transmission and isolation are analysed in detail. For enhancing the isolation between the decoupled ports, parent crossover is further modified maintaining good transmission between coupled ports. The analysis is done using ANSYS HFSS and the optimised crossover is fabricated on FR4 substrate and measurements are taken by using Keysight ENA 5080A Vector Network Analyser. The simulated and measured results are in good agreement with each other. This proposed crossover is the possible solution for long range wireless communication and GPS Applications.

Abstract: Metamaterials with negative index of refraction has created great opportunities for novel applications at Radio Frequency. Metamaterial finds applications as filters, diplexers and as frequency selective surfaces for gain enhancement in antennas. In this work open loop filters with circle, triangle and pentagonal geometries are proposed which can be configured as metamaterial for various wireless applications. These metamaterials can be energised using different feeding mechanisms like edge coupling, electromagnetic coupling, inductive coupling, capacitive coupling etc. Proposed filters are energised using edge coupled feeding mechanism which has reduce complexity compared to other techniques. Edge coupling also ensures the tunability of the filters and make them applicable for low frequency, where the conventional planar filters consumes large area. The geometrical variations in the loop are found to influence the filter characteristics and this is studied in detail. Design equations are furnished for the filters based on the extensive analysis carried out using ANSYS High Frequency Structure Simulator (HFSS) using finite element method. The current distribution and electric field of the proposed filters are also analysed in detail. Filter prototypes with optimum performance as seen in the simulations are fabricated and measured using Keysight ENA 5080A Network Analyser. Good agreement is found to exist between experimental results and the simulated results for the designed filters. A comparative study is carried out based on the frequency of operation, bandwidth and the attenuation of the three designed filters among themselves and the previous works that authors referred into.

Abstract: Multi-hop relaying is used for increasing the communication range of cognitive radio networks (CRNs). To circumvent the implied loss in throughput due to multi-hop relaying, in this paper, we propose incremental relaying (IR) for cooperative multi-hop cognitive radio networks (CMHCRNs). Two IR protocols that select a relay from the qualified relays (the relays whose received signal-to-noise-ratio (SNR) values are greater than a predefined threshold) in each hop are proposed to study the performance of the considered CMHCRN. The first protocol is named as IR based highest SNR (IR-HSNR) protocol that selects a relay with best SNR to the destination. Another one, termed as IR based highest transmit power (IR-HTP) protocol, selects a relay with highest available transmit power. Expressions for the exact outage probability and throughput are derived for both routing protocols by considering both peak-power and peakinterference constraints. Moreover, closed-form expressions for floor values of outage probability and throughput are derived for both the protocols. It is shown through numerical results that throughput of the considered system shows a concave behavior with respect to number of relaying hops for both the proposed protocols. It is further observed that the performance of the IRHSNR is superior to that of the IR-HTP, whereas the latter has lower implementation complexity.

Abstract: Cognitive wireless sensor networks (CWSNs) provide better bandwidth utilization as compared to normal wireless sensor networks. CWSNs use a technique called opportunistic spectrum access for data transfer. It also helps the network to eliminate collisions and delays in data delivery. While doing so, however, CWSNs are subject to several security threats. The attack on network availability is known as Denial of Service (DoS) attack. The Spectrum Sensing Data Falsification (SSDF) attack comes under the DoS attack. In this attack, a malicious node sends a modified spectrum sensing report so that the collaborative spectrum sensing decision become wrong and a good cognitive sensor node receives a wrong decision regarding the vacant spectrum band of other’s network. In the presence of the node cloning attack, the solution of the SSDF attack becomes even more difficult. In node cloning attack the malicious node creates many clones of the compromised node in the network. In order to confuse the collaborative spectrum sensing system, the clone nodes can send false spectrum sensing reports in a large number. The Maximum-Match Filtering (MMF) algorithm is used for making a secure spectrum sensing decision and spectrum allocation in CWSNs. In this paper we have proposed the Cloned Node Detection (CND) algorithm to detect cloned nodes. This paper also explains how the CND algorithm assists the MMF algorithm to make better spectrum sensing decisions by avoiding the node cloning attack. Our CND and MMF algorithms have O(n) and O(c 2n) worst case time complexities respectively. Our algorithms also have a very low false positive rate in the network. The MMF algorithm can produce good results with relatively small number of inputs, which reduces the traffic in the virtual control channel

Abstract: Since the global climate change altering the characteristics of extreme rainfall events, modeling the behavior of extreme rainfall is becoming indispensable. Among various physical processes, the El Niño Southern Oscillation (ENSO) cycle is a significant process that can trigger occurrences of extreme hydro-climatological events, such as floods, droughts and cyclones. Consequently, modeling the relationship between ENSO cycle and regional cli- mate anomaly is gaining more attention in recent years. Studies in literature used various ENSO indices to quantify ENSO cycle in the statistical models which aim to model/forecast extreme rainfall and fail to report the best ENSO index for modeling extreme rainfall over India. Hence, this study is carried out to answer two research questions: (1) What is the best ENSO index for modeling extreme rainfall intensity over India? (2) What is the significance of identifying the best ENSO indicator for modeling extreme rainfall intensity over India? Towards answering these questions, the change in the linear relationship between ENSO cycle and extreme rainfall over India due to the choice of ENSO cycle indicator is examined. Results of this study indicate that the ENSO index Southern Oscillation Index (SOI) is the best ENSO index for modeling extreme rainfall over India. The results also show a significant change in ENSO-Extreme rainfall relationship due to the choice of ENSO index. In particular, 42% is the average increase in correlation coefficient between monsoon season extreme rainfall and ENSO cycle when the best ENSO index is chosen instead of the second-best ENSO index and it is around 37% for the non- monsoon season.

Abstract: In several real-world applications involving decision making under uncertainty, the traditional expected value objective may not be suitable, as it may be necessary to control losses in the case of a rare but extreme event. Conditional Value-at-Risk (CVaR) is a popular risk measure for modelling the aforementioned objective. We consider the problem of estimating CVaR from i.i.d. samples of an unbounded random variable, which is either sub-Gaussian or sub-exponential. We derive a novel one-sided concentration bound for a natural sample-based CVaR estimator in this setting. Our bound relies on a concentration result for a quantile-based estimator for Value-at-Risk (VaR), which may be of independent interest.