The days where swarms of unmanned aerial vehicles (UAVs) will occupy our skies are fast approaching due to the introduction of cost-efficient and reliable small aerial vehicles and the increasing demand for use of such vehicles in a plethora of civil applications. Governments and industry alike have been heavily investing in the development of UAVs. As such it is important to understand the characteristics of networks with UAVs to enable the incorporation of multiple, coordinated aerial vehicles into the air traffic in a reliable and safe manner. To this end, this survey reports the characteristics and requirements of UAV networks for envisioned civil applications over the period 2000–2015 from a communications and networking viewpoint. We survey and quantify quality-of-service requirements, network-relevant mission parameters, data requirements, and the minimum data to be transmitted over the network. Furthermore, we elaborate on general networking related requirements such as connectivity, adaptability, safety, privacy, security, and scalability. We also report experimental results from many projects and investigate the suitability of existing communication technologies for supporting reliable aerial networking.

Survey on Unmanned Aerial Vehicle Networks for Civil Applications: A Communications Viewpoint

The role of big data in smart city

Among the panoply of applications enabled by the Internet of Things (IoT), smart and connected health care is a particularly important one. Networked sensors, either worn on the body or embedded in our living environments, make possible the gathering of rich information indicative of our physical and mental health. Captured on a continual basis, aggregated, and effectively mined, such information can bring about a positive transformative change in the health care landscape. In particular, the availability of data at hitherto unimagined scales and temporal longitudes coupled with a new generation of intelligent processing algorithms can: (a) facilitate an evolution in the practice of medicine, from the current post facto diagnose-and-treat reactive paradigm, to a proactive framework for prognosis of diseases at an incipient stage, coupled with prevention, cure, and overall management of health instead of disease, (b) enable personalization of treatment and management options targeted particularly to the specific circumstances and needs of the individual, and (c) help reduce the cost of health care while simultaneously improving outcomes. In this paper, we highlight the opportunities and challenges for IoT in realizing this vision of the future of health care.

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Health Monitoring and Management Using Internet-of-Things (IoT) Sensing with Cloud-Based Processing: Opportunities and Challenges

An automated irrigation system was developed to optimize water use for agricultural crops. The system has a distributed wireless network of soil-moisture and temperature sensors placed in the root zone of the plants. In addition, a gateway unit handles sensor information, triggers actuators, and transmits data to a web application. An algorithm was developed with threshold values of temperature and soil moisture that was programmed into a microcontroller-based gateway to control water quantity. The system was powered by photovoltaic panels and had a duplex communication link based on a cellular-Internet interface that allowed for data inspection and irrigation scheduling to be programmed through a web page. The automated system was tested in a sage crop field for 136 days and water savings of up to 90% compared with traditional irrigation practices of the agricultural zone were achieved. Three replicas of the automated system have been used successfully in other places for 18 months. Because of its energy autonomy and low cost, the system has the potential to be useful in water limited geographically isolated areas.

Automated Irrigation System Using a Wireless Sensor Network and GPRS Module

The advanced metering infrastructure of the smart grid presents the biggest growth potential in the machine-to-machine market today. Spurred by recent advances in M2M technologies, SG smart meters are expected not to require human intervention in characterizing power requirements and energy distribution. However, there are many challenges in the design of the SG communications network whereby the electrical appliances and smart meters are able to exchange information pertaining to varying power requirements. Furthermore, different types of M2M gateways are required at different points (e.g., at home, in the building, at the neighborhood, and so forth) of the SG communication network. This article surveys a number of existing communication technologies that can be adopted for M2M communication in SG. Among these, the most reliable technology to facilitate M2M communication in the SG home area network is pointed out, and its shortcoming is also noted. Furthermore, a possible solution to deal with this shortcoming to improve SG communications scalability is also presented.

Toward intelligent machine-to-machine communications in smart grid

Bluetooth (over IEEE 802.15.1), ultra-wideband (UWB, over IEEE 802.15.3), ZigBee (over IEEE 802.15.4), and Wi-Fi (over IEEE 802.11) are four protocol standards for short- range wireless communications with low power consumption. From an application point of view, bluetooth is intended for a cordless mouse, keyboard, and hands-free headset, UWB is oriented to high-bandwidth multimedia links, ZigBee is designed for reliable wirelessly networked monitoring and control networks, while Wi-Fi is directed at computer-to-computer connections as an extension or substitution of cabled networks. In this paper, we provide a study of these popular wireless communication standards, evaluating their main features and behaviors in terms of various metrics, including the transmission time, data coding efficiency, complexity, and power consumption. It is believed that the comparison presented in this paper would benefit application engineers in selecting an appropriate protocol.

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A Comparative Study of Wireless Protocols: Bluetooth, UWB, ZigBee, and Wi-Fi

High-Performance Organic Photodiodes for Blue-Light Hazard Detection

PM6:Y6 is adopted as the active layer to prepare highly efficient organic photodetectors (OPDs), which is applied to realize a biometric sensor for real‐time heart‐rate monitoring. Here, the effects of the device structure, thickness, deposition process, and solvent on the subsequent performance of the OPDs are examined. Through judicious choice of the fabrication conditions, an OPD is obtained displaying a dark current density of less than 8.77 × 10−10 A cm−2, a responsivity of greater than 0.516 A W−1, and a high detectivity of 3.1 × 1013 Jones, measured at bias of −2 V (870 nm). This OPD featured a wide linear dynamic range (LDR, 530 nm) of 104 dB at −2 V, an ultrahigh cutoff frequency (750 kHz) and rise/fall times of less than 220 ns under a reverse bias of −2 V. This sub‐microsecond response and high detectivity is comparable with, and in some cases better than, those of the state‐of‐the‐art perovskite‐PDs and Si‐PDs. The OPD displays consistent responses, good repeatability, and stability [ambient: 50% humidity, 25 °C)]. The air‐stable and portable OPD‐based photoplethysmogram system provides clear signal resolution, potentially benefitting its applicability to blood pressure monitoring.

Ambient‐Stable Near‐Infrared Organic Photodetectors with Ultrahigh Detectivity and Ultrafast Response for Biometric Monitoring

Near-infrared (NIR) small-molecule acceptors that absorb at wavelengths of up to 1000 nm are attractive for applications in organic photodetectors (OPDs) and biometrics. In this study, we incorporated IEICO-4F as the third component for PffBT4T-2OD:PC71BM-based OPDs to provide an efficient NIR response while greatly suppressing the leakage current at reverse bias. By varying the blend ratio and thickness (250-600 nm), we obtained an NIR OPD displaying an ultralow dark-current density (JD = 2.62 nA cm-2), ultrahigh detectivity [D* = 7.2 × 1012 Jones (850 nm)], high sensitivity, and photoresponsivity covering the region from the ultraviolet to the NIR. We used tapping-mode atomic force microscopy, optical microscopy, grazing-incidence wide-angle X-ray scattering, and contact angle measurements to investigate the effect of IEICO-4F on the performance of the ternary OPDs. The low compatibility of PffBT4T-2OD and IEICO-4F, originating from weak intermolecular interactions, allowed us to manipulate the degree of phase separation between the donor and acceptor in the ternary blends, leading to an optimized blend morphology featuring efficient charge separation, transport, and collection. To demonstrate its applicability, we integrated our OPD with two light-emitting diodes and used the system for precisely calculated transmissive pulse oximetry.

Yu-Wei Su

Papers

A Comparative Study of Wireless Protocols: Bluetooth, UWB, ZigBee, and Wi-Fi

High-Performance Organic Photodiodes for Blue-Light Hazard Detection

Ambient‐Stable Near‐Infrared Organic Photodetectors with Ultrahigh Detectivity and Ultrafast Response for Biometric Monitoring

Highly Efficient Ternary Near-Infrared Organic Photodetectors for Biometric Monitoring.

Indolocarbazole-based small molecules as guest donors for High-Performance ternary organic photovoltaics