Devices In Close Proximity Research Articles

How to Download More Data from Neighbors? A Metric for D2D Data Offloading Opportunity

Mobile devices in close proximity can be connected in a device-to-device (D2D) manner to transfer digital objects (e.g., videos) to each other. By using D2D data offloading, mobile users can reduce the cost for data service from wireless cellular networks. However, due to users’ mobility, the opportunity for a user to obtain his interested objects via D2D communication is transient. In this paper, we first propose an expected available duration (EAD) metric to evaluate the opportunity that an object can be downloaded by a user via D2D data offloading. The EAD metric takes into account the pairwise connectivity of users, social influence between users, diffusion of digital objects, and the time that users would like to wait for D2D data offloading. We then propose a distributed algorithm for a mobile device to determine the EAD of each object. Given a set of available objects in the neighborhood, a mobile device will first download the object that has the smallest EAD. We validate our model via trace-driven simulations. Results show that our proposed algorithm can effectively find the object that should be first downloaded. Comparing with existing schemes, our work can help users download more data via D2D data offloading.

Optimized Energy Harvesting, Cluster-Head Selection and Channel Allocation for IoTs in Smart Cities.

This paper highlights three critical aspects of the internet of things (IoTs), namely (1) energy efficiency, (2) energy balancing and (3) quality of service (QoS) and presents three novel schemes for addressing these aspects. For energy efficiency, a novel radio frequency (RF) energy-harvesting scheme is presented in which each IoT device is associated with the best possible RF source in order to maximize the overall energy that the IoT devices harvest. For energy balancing, the IoT devices in close proximity are clustered together and then an IoT device with the highest residual energy is selected as a cluster head (CH) on a rotational basis. Once the CH is selected, it assigns channels to the IoT devices to report their data using a novel integer linear program (ILP)-based channel allocation scheme by satisfying their desired QoS. To evaluate the presented schemes, exhaustive simulations are carried out by varying different parameters, including the number of IoT devices, the number of harvesting sources, the distance between RF sources and IoT devices and the primary user (PU) activity of different channels. The simulation results demonstrate that our proposed schemes perform better than the existing ones.

Towards Batteryless Cardiac Implantable Electronic Devices-The Swiss Way.

Energy harvesting devices are widely discussed as an alternative power source for todays active implantable medical devices. Repeated battery replacement procedures can be avoided by extending the implants life span, which is the goal of energy harvesting concepts. This reduces the risk of complications for the patient and may even reduce device size. The continuous and powerful contractions of a human heart ideally qualify as a battery substitute. In particular, devices in close proximity to the heart such as pacemakers, defibrillators or bio signal (ECG) recorders would benefit from this alternative energy source. The clockwork of an automatic wristwatch was used to transform the hearts kinetic energy into electrical energy. In order to qualify as a continuous energy supply for the consuming device, the mechanism needs to demonstrate its harvesting capability under various conditions. Several in-vivo recorded heart motions were used as input of a mathematical model to optimize the clockworks original conversion efficiency with respect to myocardial contractions. The resulting design was implemented and tested during in-vitro and in-vivo experiments, which demonstrated the superior sensitivity of the new design for all tested heart motions.

Improved Performance of Field Emission Vacuum Microelectronic Devices for Integrated Circuits

The movement from discrete transistors to integrated silicon circuits led to the rapid evolution of microscale electronics, but there has been no equivalent transition for the vacuum tube transistor. Difficulty integrating devices at microscales has hindered the use of vacuum electronic circuits, despite the unique advantages they offer in selected applications. The development of the field emission microfabricated cathode offers the potential to take advantage of the benefits of the vacuum technology in an integrated platform. This paper utilizes an MEMS carbon nanotube field emission vacuum microelectronic device as an active circuit element. Using a combination of particle trajectory simulation and experimental characterization, we investigated device performance in an integrated platform. Specifically, we present solutions for the operation of multiple devices in close proximity and for enhancing transmission (i.e., reducing grid loss) in vacuum field emission devices. The isolation structures reduced the crosstalk between neighboring devices from 14% on average, to nearly zero. Innovative geometries and a new operational mode reduced the grid loss by nearly three times, improving transmission of the current from the cathode to the anode from 25% from the previous designs to 70% on average. These performance enhancements are the important enablers for larger scale integration and for the realization of complex vacuum microelectronic circuits.

Concept & Technology Briefing: Near Field Communication (NFC)

Near Field Communication (NFC) is a wireless communication standard which enables two devices in a short range to establish a communication channel within a short period of time through radio waves in the 13.56 MHz frequency range. NFC can be a useful technology for data transfer between two devices in close proximity to one another. Because it needs the two devices to be in close proximity to one another (less than 10 cm), it is more secure than other wireless technologies like Bluetooth and Wi-Fi. Hence, it can be seen as an easy and secure tool for establishing quick two-way connections for data transfer. While the biggest differentiating factor for NFC over RFID is that it is a two-way communication tool, one of the devices/cards can have a passive NFC tag which can reduce the cost and still behave in the same way as any other RFID tag.

Planning at the edge: Integrating across the land sea divide

Marine Spatial Planning (MSP) is a relatively recent phenomenon. Land planning has evolved through decades of hard experience. This paper considers the origins of both marine and terrestrial planning highlighting fundamental differences. Development projects combining marine and terrestrial infrastructure, but operating in separate planning regimes, create the potential for conflict. With rising ambition to exploit marine resources there is a growing need for effective coordination between the terrestrial and marine planning systems. This paper considers marine renewable energy (wave and tide) developments which clearly represent and magnify the issues involved. Dense arrays of devices in close proximity to shore, combined marine/terrestrial operations, and coastal protected areas expose choices to high public scrutiny and introduce risk to developers. Particular reference is made to Scotland and marine renewable energy (MRE) development in the Pentland Firth and Orkney Waters (PFOW). The PFOW area is the world centre for trials of MRE devices and the subject of preparatory work and testing for MSP in all of Scottish waters. Scotland has the fourth largest marine area in Europe. This paper concludes that full integration is not achievable. The differences in governance, rights and resource use are too great. However, transboundary interactions are very significant and demand a high level of coordination and clear lines of accountability. Separation of accountability between central government responsibility for marine planning and local responsibility for terrestrial planning is not sustainable.

The Development & Implementation of Wireless Body Area Networks

The increasing use of wireless networks and the constant miniaturization of electrical devices has empowered the development of Wireless Body Area Net-works . Wireless Body Area Network is a system of devices in close proximity to a person's body that cooperate for the benefit of the user where various sensors are attached on clothing or on the body or even implanted under the skin. This paper shows several uses of the BAN technology and the most obvious application of a BAN is in the medical sector, however there are also more recreational uses to BANs. Using a WBAN, the patient experiences a greater physical mobility and is no longer compelled to stay in the hospital. This paper offers a survey of the concept of Wireless Body Area Networks. As WBANs are placed on the human body and often transport private data, security is also considered. This paper will discuss the technologies surrounding BANs, as well as several common applications for BANs.

Delivery of definitive dose external beam radiation in close proximity to an implanted deep brain stimulator

Deep brain stimulation (DBS) is an increasingly common treatment for medication-refractory Parkinson disease and essential tremor and has emerging applications for other neurologic and psychiatric conditions. 1 Miocinovic S. Somayajula S. Chitnis S. Vitek J.L. History, applications, and mechanisms of deep brain stimulation. JAMA neurol. 2013; 70: 163-171 Crossref PubMed Scopus (329) Google Scholar , 2 Okun M.S. Deep-brain stimulation for Parkinson's disease. N Engl J Med. 2013; 368: 483-484 PubMed Google Scholar The DBS system consists of 1 or more electrode leads implanted in the brain, and connected by tunneled wires to an impulse generator implanted in the subcutaneous tissue below the clavicle. The impulse generator contains a battery-powered circuit and is programmed with patient-specific stimulation. The system comes with a handheld programmer that can set stimulation parameters and turn the device on or off. Little evidence is available regarding administration of radiation therapy with a DBS device in close proximity to the target volume. In this report, we present our experience treating a patient with a DBS directly overlying a non-small cell lung tumor.

Experimental evaluation of ballistic hazards in imaging diagnostic center.

SummaryBackground:Serious hazards for human health and life and devices in close proximity to the magnetic resonance scanners (MRI scanners) include the effects of being hit by ferromagnetic objects attracted by static magnetic field (SMF) produced by scanner magnet – the so-called ballistic hazards classified among indirect electromagnetic hazards. International safety guidelines and technical literature specify different SMF threshold values regarding ballistic hazards – e.g. 3 mT (directive 2004/40/EC, EN 60601-2-33), and 30 mT (BMAS 2009, directive proposal 2011). Investigations presented in this article were performed in order to experimentally verify SMF threshold for ballistic hazards near MRI scanners used in Poland.Material/Methods:Investigations were performed with the use of a laboratory source of SMF (0–30 mT) and MRI scanners of various types. The levels of SMF in which metal objects of various shapes and 0.4–500 g mass are moved by the field influence were investigated. The distance from the MRI scanners (0.2–3T) where hazards may occur were also investigated.Results:Objects investigated under laboratory conditions were moved by SMF of 2.2–15 mT magnetic flux density when they were freely suspended, but were moved by the SMF of 5.6–22 mT when they were placed on a smooth surface. Investigated objects were moved in fields of 3.5–40 mT by MRI scanners. Distances from scanner magnet cover, where ballistic hazards might occur are: up to 0.5 m for 0.2–0.3T scanners; up to 1.3 m for 0.5T scanners; up to 2.0 m for 1.5T scanners and up to 2.5 m for 3T scanners (at the front and back of the magnet).Conclusions:It was shown that SMF of 3 mT magnetic flux density should be taken as the threshold for ballistic hazards. Such level is compatible with SMF limit value regarding occupational safety and health-protected areas/zones, where according to the Polish labor law the procedures of work environment inspection and prevention measures regarding indirect electromagnetic hazards should be applied. Presented results do not support the increase up to 30 mT of the SMF limit for protected area.

NAN: Near-me Area Network

Due to the increasing popularity of mobile Internet and location-enabled mobile devices in recent years, a new type of communication network is emerging, and we call it Near-me Area Network (NAN). It focuses on the communication among the wireless devices in close proximity, creating a new kind of application domain. In this article, we will introduce NAN, review the existing applications, and most importantly point out the challenges for the NAN applications.

The Near-Me Area Network

The mobile Internet and location-enabled mobile devices have become increasingly popular, inspiring a new type of communication network. This near-me area network (NAN) focuses on communication among wireless devices in close proximity, creating a new kind of application domain. This article introduces NAN and reviews existing applications and challenges.

A Passive Heterodyne Hot Electron Bolometer Imager Operating at 850 GHz

We report on the development and characterization of a passive heterodyne hot electron bolometer (HEB) imager operating at 850 GHz. HEB detectors provide unprecedented sensitivity and spectral resolution at terahertz frequencies covering the frequency range of 0.5-5 THz. Terahertz imagers based on HEB technology have sufficient sensitivity to operate in a passive imaging mode, thus eliminating the need for active illumination. We demonstrated a fully automated passive imaging system based on our HEB technology. The front-end heterodyne detector includes a quasi-optically coupled HEB device in close proximity to a monolithic microwave integrated circuit low-noise IF amplifier. We integrated a compact commercial harmonic multiplier local oscillator (LO) source to provide the LO biasing for the HEB detector. Our high spectral resolution terahertz imager has a noise equivalent temperature difference value of 0.4 K and a spatial resolution of approximately 4 mm.

Nonequilibrium charge noise and dephasing from a spin-incoherent Luttinger liquid

We theoretically investigate the charge noise and dephasing in a metallic device in close proximity to a spin incoherent Luttinger liquid with a small but finite current. The frequency dependence of the charge noise exhibits a loss of frequency peaks corresponding to the $2k_F$ part of the density correlations in the electron liquid when the temperature $T$ is increased from values below the magnetic exchange energy $J$ of the electron gas to values above it. The dephasing rate in a nearby metallic nanostructure also shows a cross-over for $T \sim J$ and may exhibit a non-monotonic temperature dependence. For a range of temperatures the dephasing rate {\em decreases} with increasing temperatures. The proposed experiments provide a convenient approach to probe the spin-incoherent Luttinger liquid and should be implementable in a wide variety of systems.

Modeling of the thermal effects of heat generating devices in close proximity on vertically oriented printed circuit boards for thermal management applications

The localized thermal interactions between adjacent devices on vertically orientated circuit boards in natural convection are predicted using experimentally validated computational fluid dynamics models. The effects of power density, device proximity, device geometry, circuit board material, board packing density and board separation distance on the steady state operating temperatures are investigated and incorporated into mathematical models which can be used to design packages which minimize thermal interactions. The separation distance beyond which the devices do not thermally influence each other is identified and the influence of various parameters on this distance is studied. The parametric study is designed using Design of Experiments methodology and therefore can be used to interpret the interaction between independent parameters. The developed models and methodology can easily and quickly be applied to other packaging situations to help minimize negative thermal interactions as one consideration in board layout design.

Interpretation of current flow in photodiode structures using laser beam-induced current for characterization and diagnostics

This paper presents an interpretation of the physical mechanisms involved in the generation of laser beam-induced current (LBIC) in semiconductor p-n junction diodes. LBIC is a nondestructive semiconductor characterization technique that has been used in a qualitative manner for a number of years and is especially useful for examining individual photodiodes within large two-dimensional arrays of devices. The main thrust of this work is the analysis of LBIC in terms of nonzero steady-state circulatory current flow within the device and, hence, the interpretation of LBIC line profiles to diagnose the patterns of current flow within the structure. This provides an important basis for future studies seeking to relate LBIC to indicators of p-n junction performance and integrity such as dark current components and reverse bias saturation current. In particular, this paper examines the ideal cases of a single isolated p-n junction diode structure, and also considers an array of such devices in close proximity to each other. Modifications to the idealized theory that are required to account for localized junction leakage and surface recombination are presented, and the effect of Schottky contacts is discussed. Numerical simulations based on the HgCdTe family of semiconductors are presented to support the theory.

Ultra-Wideband Signal Impact on the Performances of IEEE 802.11b and Bluetooth Networks

This paper presents the results of a coexistence study investigating the impact of ultra-wideband (UWB) interference on IEEE 802.11b and Bluetooth networks. The results are based on the experimental test measurements made at the University of Oulu, Finland. Simple high-power UWB transmitters are used to interfere with victim networks. Preliminary results show that only under extreme interference conditions with thousands of equivalent Federal Communications Commission– (FCC)-compliant devices in close proximity, will the IEEE 802.11b and Bluetooth networks experience significant performance degradation. The impact of the UWB interference on the IEEE 802.11b network was insignificant if the distance to UWB transmitters was greater than 40 cm. The impact on Bluetooth was even less noticeable. In our study, several high-power UWB transmitters that greatly exceed the FCC radiation regulations have been used, and the measurement settings presents the worst case scenario because of the very short distance between the interferers and the victim system. Effectively our study approximates the use of thousands of FCC-complaint UWB devices in the same space.

Experimental investigation into low pressure gas discharges in microwave electric field optical sensor probes

This paper investigates the feasibility of using the emission intensity of low‐pressure argon and nitrogen gas discharges as the sensing mechanism for a microwave electric field optical sensor probe in microwave resonant cavities. The emission is coupled to a photodiode for detection through an optical fibre due to the difficulty in using conventional optoelectronic devices in close proximity to microwave cavities. The discharge emission intensity is monitored at a range of different input powers to the cavity. The proposed designs for the electric field sensing probe are also included.

A Study on Safety Functional Design for FA Systems Using Safety Index

The installation of various equipments and devices in close proximity necessitate the establishment of a design method capable of securing safety in a systematic manner. Regarding the safety index worked out for the sake of safety evaluation, including the reliability of safety devices, and the attention of operators/maintenance personnel, it is necessary to prepare the TAS (Tree Analysis for Safety) at each FA system, and though it is suitable to a system safety evaluation, it is inappropriate as a system safety functional design. In this paper, I show that the degree of surplus indicating the degree of accomplishment of the safety standard at each logical product can be defined. Using this degree of surplus, I propose the method seeking a combination of safety devices which can cope with the multiplexing of safety devices. Thus, I show that the safety functional design for FA systems can be constructed using the safety index

A simulation study of IC layout effects on thermal management of die attached GaAs ICs

Power management and thermal characterization of integrated power amplifiers is crucial to the development of a number of advanced technologies including portable wireless applications. Reduction and or optimization of device operating temperatures and thermal characteristics is needed to control temperature activated failure phenomena. This paper presents the use of PATRAN, a three-dimensional (3-D) model builder and finite element method (FEM) solver as means of understanding the heat flow in integrated devices and optimizing the layout for thermal operation. The approach taken is to assume a priori knowledge of the heat generation region and decouple the semiconductor transport equations. This allows for solution of the heat equation over a sufficiently large region to be correct. After verifying the correctness of the assumption of the device temperature being relatively insensitive to the depth, thickness and shape of the heat generation region, the optimization of heat spreaders in a GaAs HBT process is presented. This optimization is performed as an example of how both the maximum temperature and temperature variation across the emitter can reduced by careful design of the emitter metallization. Finally, the use of PATRAN is presented for extracting a three resistor thermal model for two devices in close proximity.

Low noise refrigerant compressor

A sound barrier cover for a compressor unit which has a housing provided by a substantially continuous wall which provided with a plurality of access ports therethrough. The barrier cover has first and second shell sections configured to lie close to the housing wall and substantially envelope the same wherein the shell sections are configured to provide two substantially longitudinally oriented halves each having sound absorbing material affixed to its inner surface. These halves have perimeters with portions thereof formed with mating tongue and groove structure and carry cooperating components of snap-fastener devices in close proximity to the perimeters. These snap-fastener devices are adapted to hold the perimeters in contact with each other and with the sound absorbing material in resilient contact with the housing.