1,875 research outputs found

    CBRS Spectrum Sharing between LTE-U and WiFi: A Multiarmed Bandit Approach

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    The surge of mobile devices such as smartphone and tablets requires additional capacity. To achieve ubiquitous and high data rate Internet connectivity, effective spectrum sharing and utilization of the wireless spectrum carry critical importance. In this paper, we consider the use of unlicensed LTE (LTE-U) technology in the 3.5 GHz Citizens Broadband Radio Service (CBRS) band and develop a multiarmed bandit (MAB) based spectrum sharing technique for a smooth coexistence with WiFi. In particular, we consider LTE-U to operate as a General Authorized Access (GAA) user; hereby MAB is used to adaptively optimize the transmission duty cycle of LTE-U transmissions. Additionally, we incorporate downlink power control which yields a high energy efficiency and interference suppression. Simulation results demonstrate a significant improvement in the aggregate capacity (approximately 33%) and cell-edge throughput of coexisting LTE-U and WiFi networks for different base station densities and user densities

    Optimizing seed rate for summer mungbean varieties

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    An experiment was conducted at the Agronomy Field Laboratory, Bangladesh Agricultural University, Mymensingh from March to June, 2007 to investigate the effect of cultivar and seed rate on morphological characters, yield attributes and yield of summer mungbean. The experiment comprised four varieties viz., BINA moog2, BINA moog5, BINA moog6 and BINA moog7 and four seed rates viz. 30, 40, 50 and 60 kg ha-1. The experiment was laid out in a randomized complete block design with four replications. Results revealed that variety and seed rate had significant effect on the studied crop characters and yield. The variety BINA moog7 showed superiority in relation to plant height, number of branches and effective pods per plant, number of seeds pod-1 compared to other varieties, which resulted in the highest seed yield both per plant and per hectare. The plant height, stover yield and number of non-effective pods per plant increased with the increase in seed rate, while branch number, number of effective pods per plant, seeds per pod, 100-seed weight, as well as seed weight per plant decreased with increasing seed rate. The higher number of branches and effective pods per plant, number of seeds pod, 100-seed weight and seed yield per plant were recorded at the rate of 30 and 40 kg seeds ha-1 and the lowest values for the above parameters were observed at the rate of 60 kg seeds ha-1. But per unit area basis, the highest seed yield was recorded in 40 kg seeds ha-1 followed by 50 kg seeds ha-1 due to accommodation of higher number of plants. BINA moog7 interacted favorably with the seed rate of 30 kg ha-1 to produce the highest seed yield

    Process involved in designing of an intelligent additional track mechanism tracked vehicle for swamp peat terrain

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    Different types of off road vehicles are widely used in agriculture, oil industry, mining and military operations but none of them can effectively operate over the swamp peat terrain because of its low bearing capacity of 7kN/m 2. Segmented rubber tracked vehicle and intelligent air-cushion system tracked vehicle were developed in Malaysia for swamp peat terrain.16kN/m2 of ground pressure was exerted by using the segmented rubber tracked vehicle during field operation therefore could not be operated efficiently. The air-cushion tracked vehicle increased the floatation capacity but at the same time increased the frictional effects therefore the tracks of the vehicle easily slipped out from the traction wheels during operation. Addressing these issues an intelligent additional track mechanism for tracked vehicle has been designed to improve the mobility over swamp peat terrain where the additional track would be increased the ground surface area and reduced the vehicle ground pressure. This paper presents the process involved in designing the intelligent additional track mechanism tracked vehicle for transportation of agricultural and industrial goods on the swamp peat terrain with bearing capacity of 7kN/m2. The mechanical design comprises of track vehicle frame with track mechanism. Additional track mechanism with Fuzzy expert system. The design parameters are optimized using developed mathematical model based on the dynamics and kinematics behavior of the vehicle. In order to increase the vehicle contact surface area and reduce the surface contact pressure the additional track mechanism is designed in such way that it can be folded and unfolded from its position by using the ball-screw scissor lift mechanism. While, Fuzzy expert system is used to control the movement of the lift mechanism based on 70mm critical sinkage of vehicle detected from a set of sensors. The completed to vehicle system would be used for off-road applications as required

    Lower bounds on the dilation of plane spanners

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    (I) We exhibit a set of 23 points in the plane that has dilation at least 1.43081.4308, improving the previously best lower bound of 1.41611.4161 for the worst-case dilation of plane spanners. (II) For every integer n13n\geq13, there exists an nn-element point set SS such that the degree 3 dilation of SS denoted by δ0(S,3) equals 1+3=2.7321\delta_0(S,3) \text{ equals } 1+\sqrt{3}=2.7321\ldots in the domain of plane geometric spanners. In the same domain, we show that for every integer n6n\geq6, there exists a an nn-element point set SS such that the degree 4 dilation of SS denoted by δ0(S,4) equals 1+(55)/2=2.1755\delta_0(S,4) \text{ equals } 1 + \sqrt{(5-\sqrt{5})/2}=2.1755\ldots The previous best lower bound of 1.41611.4161 holds for any degree. (III) For every integer n6n\geq6 , there exists an nn-element point set SS such that the stretch factor of the greedy triangulation of SS is at least 2.02682.0268.Comment: Revised definitions in the introduction; 23 pages, 15 figures; 2 table

    CITRIC: A low-bandwidth wireless camera network platform

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    In this paper, we propose and demonstrate a novel wireless camera network system, called CITRIC. The core component of this system is a new hardware platform that integrates a camera, a frequency-scalable (up to 624 MHz) CPU, 16 MB FLASH, and 64 MB RAM onto a single device. The device then connects with a standard sensor network mote to form a camera mote. The design enables in-network processing of images to reduce communication requirements, which has traditionally been high in existing camera networks with centralized processing. We also propose a back-end client/server architecture to provide a user interface to the system and support further centralized processing for higher-level applications. Our camera mote enables a wider variety of distributed pattern recognition applications than traditional platforms because it provides more computing power and tighter integration of physical components while still consuming relatively little power. Furthermore, the mote easily integrates with existing low-bandwidth sensor networks because it can communicate over the IEEE 802.15.4 protocol with other sensor network platforms. We demonstrate our system on three applications: image compression, target tracking, and camera localization

    From Horndeski action to the Callan-Giddings-Harvey-Strominger model and beyond

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    The knowledge of what entered black hole (BH) is completely lost as it evaporates. This contradicts the unitarity principle of quantum mechanics and is referred to as the information loss paradox. Understanding the end stages of BH evaporation is key to resolving this paradox. As a first step, we need to have exact models that can mimic 4-D BHs in General relativity in classical limit and have a systematic way to include high-energy corrections. While there are various models in the literature, there is no systematic procedure by which one can study high-energy corrections. In this work, for the first time, we obtain Callan, Giddings, Harvey, and Strominger (CGHS) -- a (1+1)-D -- model from 4-D Horndeski action -- the most general scalar-tensor theory that does not lead to Ostrogradsky ghosts. We then show that 4-D Horndeski action can systematically provide a route to include higher-derivative terms relevant at the end stages of black hole evaporation. We derive the leading order Hawking flux while discussing some intriguing characteristics of the corrected CGHS models. We compare our results with other works and discuss the implications for primordial BHs.Comment: V2: Version accepted in PRD Letters. The title is modified. 34 Pages, 4 figures (including supplementary material
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