Short Devices Research Articles

Optimizations of Si PIN diode phase-shifter for controlling MZM quadrature bias point using SOI rib waveguide technology

Commercial high-speed silicon (Si) Mach-Zehnder modulator (MZM) required to be active around the quadrature bias point (linear transmission area) with low power consumption, small footprint, and small drive voltage. The bias controlling is done by an optical phase-shifter (PS). However, the accuracy is limited by the drive voltage, laser thermal drift, and fabrication errors. To overcome these problems, we propose in this paper the study and analysis of Si PIN diode PS under forward biasing at 1550 nm wavelength using the standard 220 nm substrate silicon-on-insulator (SOI) rib waveguide technology. Numerical investigations were carried out on the key geometrical parameters, doping concentration, doping locations, operating wavelength, biasing level. Results show that the optimal design can be operated with a lower voltage (Vπ = 1.629 v), lower attenuation (α = 28.985 dB/cm), and short device length with an extremely small voltage-length product VπL = 0.815 vmm. Thus, this PS can be used for designing an efficiency high-speed MZM and to obtain better performances in the optical commutation system.

Simulation of single-phase ground short circuit protection device

The most common type of short circuit in a three-phase system is a single-phase-to-ground short circuit, accounting for 70 to 90% of electrical faults. In this paper simulation of the protective device from single-phase-to-ground short circuit with automatic change of current setting in electrical networks of 6-10 kV voltage on the basis of Coloured Petri Net is considered. The complexity of elaborated technical systems makes the problem of their modelling actual at the stage of development with the purpose of obtaining estimations of prospective and achievable characteristics. Now the modelling theory of the dynamic discrete systems, based on the formalism of Coloured Petri Nets has a wide application. Petri Net, describing the device operation, was designed and analysed using CPN Tools Programm. The resulting Petri net is correct, as it is live, reversible and safe. Thereby designed device can provide the selective protection from single-phase-to-ground short circuit.

QoS-Aware Energy Management and Node Scheduling Schemes for Sensor Network-Based Surveillance Applications

Recent advances in wireless technologies have led to an increased deployment of Wireless Sensor Networks (WSNs) for a plethora of diverse surveillance applications such as health, military, and environmental. However, sensor nodes in WSNs usually suffer from short device lifetime due to severe energy constraints and therefore, cannot guarantee to meet the Quality of Service (QoS) needs of various applications. This is proving to be a major hindrance to the widespread adoption of WSNs for such applications. Therefore, to extend the lifetime of WSNs, it is critical to optimize the energy usage in sensor nodes that are often deployed in remote and hostile terrains. To this effect, several energy management schemes have been proposed recently. Node scheduling is one such strategy that can prolong the lifetime of WSNs and also helps to balance the workload among the sensor nodes. In this article, we discuss on the energy management techniques of WSN with a particular emphasis on node scheduling and propose an energy management life-cycle model and an energy conservation pyramid to extend the network lifetime of WSNs. We have provided a detailed classification and evaluation of various node scheduling schemes in terms of their ability to fulfill essential QoS requirements, namely coverage, connectivity, fault tolerance, and security. We considered essential design issues such as network type, deployment pattern, sensing model in the classification process. Furthermore, we have discussed the operational characteristics of schemes with their related merits and demerits. We have compared the efficacy of a few well known graph-based scheduling schemes with suitable performance analysis graph. Finally, we study challenges in designing and implementing node scheduling schemes from a QoS perspective and outline open research problems.

Contact resistance corrected-electrical characteristics with channel length effects in π-conjugated small-molecule benzanthracene organic thin film transistors

In this work, bottom-contact p-type organic thin-film transistors based on small-molecule benzanthracene with various channel lengths were fabricated, characterized, and theoretically investigated. The fabricated devices showed a pronounced shift for threshold voltage as the function of channel length. Electrical parameters characterizing fabricated devices have been systematically evaluated as a function of channel length with and without contact resistance in the calculation. Contact resistance (Rc) and channel resistance (Rch) are extracted individually using the transfer line method (TLM) for output characteristic curves that were done only at low drain voltage (linear regime). The effect of contact resistance on the values of various OTFTs parameters is more pronounced in short channel length devices. The obtained results revealed that the linear regime's corrected mobilities of short channel devices are about 15% smaller than uncorrected mobility. Comparatively, the corrected threshold voltage values were found to be nearly close to uncorrected values for all channel lengths. The analytical model was also applied to reproduce output characteristics in the linear regime of different channel lengths devices with or without contact resistance. It was found that the calculated results were in good agreement with the measured results (when considering the effect of contact resistance), which confirms that the used model can correctly describe the charge transport in these kinds of devices.

КІБЕРБЕЗПЕКА БЕЗПРОВОДОВИХ СМАРТ-СИСТЕМ: КАНАЛИ ВТРУЧАНЬ ТА РАДІОЧАСТОТНІ ВРАЗЛИВОСТІ

The subject of this study is the radio frequency cyber vulnerability of information and control interaction technology in the wireless smart systems (WSS). WSS is the cyber-physical systems, that operate within the OSI model. The specificity and specialization of these systems are determined by radio technologies of the physical layer. For example, the Internet of Things (IoT, including medical IoMT), the Internet of Drones (IoD), systems for aviation monitoring ADS-B and traffic management ATM, and, in the future, the Internet of Everything (IoE) - all are types of WSS. The aim is to analyze the radio frequency parameters of information and control interaction in the WSS to identify possible radio frequency cyber vulnerabilities in the WSS. Objectives: summarize and systematize the physical and functional parameters of wireless technologies in the ISM (Industrial Scientific & Medical Band) and SRD (Short range devices) ranges, which are significant from the WSS radiofrequency cyber vulnerability perspective, including navigation technologies; analyze trends and methods of successful cyber attacks on the WSS; carry out expert assessments of potential WSSs cyber vulnerabilities depending on their architecture and application area. The methods used: analysis of trends in known radiofrequency incidents and expert assessments of the cyber vulnerability of the WSS information and control interaction channels. The following results were obtained: 12 actual WSS radio technologies were analyzed. 6 types of possible radio frequency cyber attacks on the WSS were typified. The expert assessment of the probability of exploiting vulnerabilities by ranges, radio technologies, and attack type was made. The special danger of high-tech targeted APT attacks, as well as the high potential radio vulnerability of cyber-physical systems, was shown. The cyber vulnerability of ADS-B aircraft systems was especially noted. Conclusions. The scientific novelty of the results obtained is as follows: a trend of APT attacks cost reduction and an increase in the probability of their implementation through the new capabilities of SDR technology (Software Defined Radio) were revealed. The possibility of a controlled SDR compromising of the security parameters of WSS channels in any radio range was shown. A promising direction of research was proposed - SDR-penetration testing of WSS.

Surface Photochemical Corrosion as a Mechanism for Fast Degradation of InGaN UV Laser Diodes.

We studied degradation mechanisms of ultraviolet InGaN laser diodes emitting in the UVA range. Short wavelength nitride devices are subjected to much faster degradation, under the same packaging and testing conditions, than their longer wavelength counterparts. Transmission electron microscopy analysis of the degraded laser diodes showed pronounced damage to facets in the area of the active layer (waveguide, quantum wells, and electron blocking layer). Energy-dispersive X-ray spectroscopy showed that the active layers were heavily oxidized, forming a compound close in composition to Ga2O3 with proportional addition of Al in the respective area. The oxidation depth was roughly proportional to the intensity of the optical field. We propose UV-light-induced water splitting on a semiconductor surface as a mechanism of the oxidation and degradation of these devices.

Availability of totally implantable venous access devices in cancer patients is high in the long term: a seven-year follow-up study

PurposeTotally implantable venous access devices (TIVADs) currently have an important place in medical oncology practice; however, their long-term availability deserves further investigation, since they are usually required by patients for prolonged periods. This study aimed to evaluate long-term availability of TIVADs in adult cancer patients, in conjunction with complication/removal rates over time and associated risk factors during 7-year follow-up.MethodsA total of 204 adult cancer patients who underwent TIVAD placement via subclavian vein using the Seldinger technique were included in this study. Medical data and catheter follow-up records were investigated retrospectively. Complications and port removals due to complications were evaluated over time.ResultsDuring median 21.9 (range, 0.7–82.9) months of follow-up, great majority of the patients did not require catheter removal due to complications (91.7%). During a total follow-up of 183,328 catheter days, 20 (9.8%) patients had complications with an incidence of 0.109 cases per 1000 catheter days and 18 (8.8%) of them required TIVAD removal (0.098 cases per 1000 catheter days). Most device removals due to complications (15/18, 83.3%) occurred within the first 24 months. Multivariate analysis identified left-sided device location as the only significant independent predictor of short device availability (OR, 3.5 [95% CI, 1.1–11.1], p = 0.036).ConclusionTIVADs in cancer patients appear to be safe and their availability appears to be high in the long term. A decision for early removal might be revisited. Opting for the accustomed side (right side in the present study) for implantations seems to be associated with better outcomes.

Management and Maintenance of Electrical Equipment in Industrial Facilities: Procedures for Improving Safety While Saving Money

This article discusses the importance of managing developed electrical preventive maintenance (EPM) programs, challenges resulting from underdeveloped EPM approaches, and methods for implementing and managing these initiatives. Electrical equipment that has not been properly maintained can impact worker safety due to undocumented and unknown conditions. With aging infrastructure and modifications to electrical systems through time, previously calculated short circuit capacities, arc-flash hazards, and device coordination may not reflect the installed electrical system. Performing preventive maintenance on electrical systems at industrial facilities, especially low-voltage systems, can be more difficult during economic downtimes. Justifying the costs associated with maintaining and/or upgrading systems can be challenging.

Adiabaticity engineering in optical waveguides.

The fast quasi-adiabatic dynamics (FAQUAD) protocol has proven to be an effective approach to provide shortcuts to adiabatic light evolution in optical waveguides, resulting in short and robust devices. However, the FAQUAD approach of homogeneously distributing device adiabaticity only works for a single mode (polarization, wavelength, or spatial mode group) system. We propose an adiabaticity engineering approach to redistribute the adiabaticity of optical waveguides in multi-mode systems. By engineering the adiabaticity distribution using a single control parameter, we obtain shortcuts to adiabaticity in optical waveguides for multi-mode systems. The concept is applied to the design of a compact polarization-independent adiabatic 3-dB coupler on silicon.

A Special Total-Ionizing-Dose-Induced Short Channel Effect in Thin-Film PDSOI Technology: Phenomena, Analyses, and Models

A special total-ionizing-dose-induced short channel effect in thin-film partially depleted silicon-on-insulator (PDSOI) technology is found. Short devices suffer more significant total-ionizing-dose-induced threshold voltage shift of the front-gate main transistor. The devices under pass-gate (PG) bias show worse threshold voltage shift of the front-gate main transistor than the devices under ON bias, which reveal that the trapped charges in the buried oxide layer are more responsible for these phenomena. Through the simulation of the electric field under PG bias by TCAD, we found that devices with different lengths can be uniformly divided into four regions. Then we combined the partially full depletion model with charge-sharing model and made a qualitative analysis of this effect. On this basis, we proposed a quantitative analysis model. Through this model, we can calculate the threshold voltage shift of the front-gate main transistor through the threshold voltage shift of back-gate main transistor.

Three‐ and Four‐Coordinate, Boron‐Based, Thermally Activated Delayed Fluorescent Emitters

AbstractRecent developments in purely organic‐material‐based thermally activated delayed fluorescence (TADF) emitters are helping to make them suitable for commercial applications in the near future. In spite of their high external quantum efficiencies, the broad emission spectra and short device lifetimes are the main barriers to using TADF emitters. Among the classes of materials, boron‐embedded polycyclic aromatic compounds have shown potential as TADF emitters that overcome the technical issues. In particular, highly efficient boron‐based TADF emitters with the advantage of a narrowband emission spectrum have been reported recently relying on the concept of a multi‐resonance effect. Hence, boron TADF emitters have the potential to become next‐generation emitters. Based on the future scope of the boron‐based TADF emitters (especially in development of blue TADF emitters), three‐ and four‐coordinate boron TADF emitters are reviewed. Additionally, future prospects of boron‐based TADF emitters are discussed to resolve the issues of low efficiency and short lifetimes of blue emitters.

An optimisation and sizing of photovoltaic system with supercapacitor for improving self-consumption

On-Grid photovoltaic household-prosumers systems without energy storage typically undergo many fast and short-term energy flows to and from the grid due to the solar irradiation fluctuation and rapid local fluctuations of load. This negatively affects grid system stability and decreases renewable energy system self-consumption and efficiency. Battery energy storage may resolve these issues; however, with considerable investment and maintenance cost, they usually involve unreasonable expenditure. On the other hand, supercapacitors are the most promising, cheap and no maintenance, a short-time electrical energy storage device. Due to long-term reliability and very-high current in a short-time, they can be used as short term power backup and grid stabilisation device. In this work a photovoltaic system working with a supercapacitor device demonstrates its large potential in self-consumption improvement and in grid stabilisation. The optimal supercapacitor size configuration is determined by a technical assessment. The evaluated results show that by adding small but fast-response energy storage, self-consumption can be increased as much as 83% and 114% for a sunny and partly cloudy day, respectively, in reference to the system without any local energy storage and the yearly averaged self-consumption increase for the presented load exceeds 100%. The additional benefit is grid fluctuation decrease which is found to be a significant problem in the near future and the reason for the possible penalties for poor energy quality dispatch to the grid. In this work the issue related to the analysis uncertainty due to the load temporal resolution is also presented.

In-Vivo Microsystems: A Review.

In-vivo sensors yield valuable medical information by measuring directly on the living tissue of a patient. These devices can be surface or implant devices. Electrical activity in the body, from organs or muscles can be measured using surface electrodes. For short term internal devices, catheters are used. These include cardiac catheter (in blood vessels) and bladder catheters. Due to the size and shape of the catheters, silicon devices provided an excellent solution for sensors. Since many cardiac catheters are disposable, the high volume has led to lower prices of the silicon sensors. Many catheters use a single sensor, but silicon offers the opportunity to have multi sensors in a single catheter, while maintaining small size. The cardiac catheter is usually inserted for a maximum of 72 h. Some devices may be used for a short-to-medium period to monitor parameters after an operation or injury (1–4 weeks). Increasingly, sensing, and actuating, devices are being applied to longer term implants for monitoring a range of parameters for chronic conditions. Devices for longer term implantation presented additional challenges due to the harshness of the environment and the stricter regulations for biocompatibility and safety. This paper will examine the three main areas of application for in-vivo devices: surface devices and short/medium-term and long-term implants. The issues of biocompatibility and safety will be discussed.

Short or long intramedullary devices for hip fracture? A systematic review of the evidence

Trochanteric hip fractures may be fixed with either sliding hip screws or intramedullary devices. Current UK guidance is that intramedullary fixation should be used for AO/OTA 31A3 fractures but does not stipulate length of nail. We present a systematic review comparing short and long nails for these injuries in older patients.Three studies were randomized, all with methodological concerns. None demonstrated a clinically significant difference in outcome.There is no good evidence to support long over short intramedullary devices in this scenario. Evidence is required to demonstrate whether the potentially increased surgical risk confers any benefits in this group.

Influences of increasing gate stem height on DC and RF performances of InAlAs/InGaAs InP-based HEMTs* *Project supported by the National Natural Science Foundation of China (Grant No. 61434006).

The T-gate stem height of InAlAs/InGaAs InP-based high electron mobility transistor (HEMT) is increased from 165 nm to 250 nm. The influences of increasing the gate stem height on the direct current (DC) and radio frequency (RF) performances of device are investigated. A 120-nm-long gate, 250-nm-high gate stem device exhibits a higher threshold voltage (V th) of 60 mV than a 120-nm-long gate devices with a short gate stem, caused by more Pt distributions on the gate foot edges of the high Ti/Pt/Au gate. The Pt distribution in Schottky contact metal is found to increase with the gate stem height or the gate length increasing, and thus enhancing the Schottky barrier height and expanding the gate length, which can be due to the increased internal tensile stress of Pt. The more Pt distributions for the high gate stem device also lead to more obvious Pt sinking, which reduces the distance between the gate and the InGaAs channel so that the transconductance (g m) of the high gate stem device is 70 mS/mm larger than that of the short stem device. As for the RF performances, the gate extrinsic parasitic capacitance decreases and the intrinsic transconductance increases after the gate stem height has been increased, so the RF performances of device are obviously improved. The high gate stem device yields a maximum f t of 270 GHz and f max of 460 GHz, while the short gate stem device has a maximum f t of 240 GHz and the f max of 370 GHz.

Data Transmission and Management Based on Node Communication in Opportunistic Social Networks

Due to the rapid popularization of various short distance communication mobile devices, the use scenarios of opportunistic networks are increasing day by day. However, in opportunistic networks, because of the complexity of community structure, many methods lack of symmetry between application and theoretical research. Thus, the connection strength between nodes is different, and the degree of message diffusion is different. If the above factors cannot be accurately estimated and analyzed, and effective data forwarding and scheduling strategies cannot be formulated, the delivery ratio will be low, the delay will be relatively high, and the network overhead will be large. In light of improving symmetry problems in opportunistic networks, this paper establishes the message duplicate adaptive allocation and spray routing strategy (MDASRS) algorithm model, measures the connection strength between nodes through social pressure, and estimates the diffusion of current messages in the network through the probability of messages leaving the current node successfully, so as to develop the self-adaptive control replication transmission mode and achieve the effect of reducing the network burden and network overhead. This is done through experiments and comparison of social network algorithms, comparing the MDASRS with Epidemic, Spray and Wait, and EIMST algorithms. The experiment results showed that this method improves the cache utilization of nodes, reduces data transmission delay, and improves the network’s overall efficiency.

The Leap from Organic Light-Emitting Diodes to Organic Semiconductor Laser Diodes

In recent years, organic light-emitting device technology has expanded from organic light-emitting diodes (OLEDs) to organic semiconductor laser diodes (OSLDs) with the progress of sophisticated mo...

Preliminary results of spot-stent grafting in Stanford type B aortic dissection and intramural haematoma.

Optimal treatment for patients with diseased proximal landing zones in acute/subacute Stanford type B dissection and intramural haematoma remains unclear. This study describes the preliminary outcomes of a localized endovascular treatment [spot-stent grafting (SSG)] of main entries/intramural blood pooling located downstream (aortic zones 4 and 5) using one single short device comprising diseased landing zones, looking particularly at the technical and morphological outcomes. Patients undergoing thoracic endovascular aortic repair (TEVAR) for acute/subacute aortic dissection Stanford type B/intramural haematoma Stanford type B between 1997 and 2018 were identified from a prospectively maintained institutional database. In a total of 183 cases, 22 patients (7 women; median age 62 years; range 35-79 years) received SSG. The primary study end point was technical success. The primary morphological end point was false lumen thrombosis/aortic remodelling. Secondary end points were TEVAR-related mortality/morbidity and reinterventions. The median follow-up was 28.5 months (5 days-15.6 years). The primary technical success rate was 100% (22/22). During follow-up, false lumen thrombosis was seen in 21 patients (95.5%) at a median of 6 days (0 days to 2.7 years) after the index procedure (limited/extended false lumen thrombosis: n = 9 vs 12). Aortic remodelling was achieved in 15 of 22 patients (68.2%) at a median of 360 days (3 days to 7.2 years). Limited/extended remodelling was observed in 8/15 and 7/15, respectively. Retrograde dissection or stent graft-induced new entry was not observed. No stroke or spinal cord injury occurred. Reinterventions were performed in 4/22 cases. The in-hospital mortality and 30-day mortality were 0%. Overall mortality during the follow-up period was 22.7% (5/22). This study shows favourable technical and morphological results for SSG in selected patients with acute/subacute aortic dissection Stanford type B/intramural haematoma Stanford type B. Patient allocation to SSG remains individual. Prospective large-scale long-term data may allow refinement of the application.

Power optimization with less state transition for green software defined networking

The power consumed by the Internet industry has been growing sharply in recent years, which accounts for a considerable proportion of the overall power consumption. To reduce high power consumption in the network, numerous proposals on power-saving are proposed. However, they usually reduce power consumption by dynamically sleeping and awakening the network device according to the current traffic fluctuation. When the traffic fluctuate sharply, the network device will swing between sleep and active state frequently, which consumes a considerable power and causes a series of side effects, such as packet losses, short sustainable device service life and synchronization among devices.In this paper, based on Software Defined Networking (SDN), we propose a Power Optimization with Less State Transition (POLST) framework, which mainly achieves the following two functions: (1) Real-time network monitoring with high accuracy and low overhead; (2) Power optimization with less device state transition. Then, we formulate optimization problem of minimizing the network power consumption, while considering power consumed by device state transition. To solve it, we propose a Power Aware Routing with Less State Transition (PARLST) algorithm. Finally, simulation results show that compared with the benchmarks, POLST has excellent performance in both network monitoring and network power optimization. More specifically, in the network monitoring, POLST can achieve up to 97.2% measurement accuracy with low monitoring overhead. In the power optimization, in comparison to the benchmarks, POLST can achieve up to 72.2% energy efficiency, 56.6% decrease in Switch State Transition (SST), 53.5% decrease in Link State Transition (LST).

Ultra-low NA step-index large mode area Yb-doped fiber with a germanium doped cladding for high power pulse amplification.

High concentration rare earth doped, large mode area (LMA) step-index fibers, which feature a very high cladding absorption per unit length at the pump wavelength, high efficiency, and excellent beam quality, are ideal for high power pulsed fiber lasers/amplifiers where large effective mode areas and short device lengths are crucial in order to reduce detrimental nonlinear effects associated with high peak power operation. In this Letter, we realize low numerical aperture (NA) high absorption fibers, simply by employing a germanium (Ge)-doped cladding rather than a pure silica cladding to offset the high refractive index associated with using a high concentration of ytterbium (Yb) in the core. This approach allows us to separate the two inter-linked fiber design parameters of pump absorption and NA in a step-index fiber. Using a conventional modified chemical vapor deposition process combined with solution doping, a low NA (0.04), LMA (475µm2) silica fiber is fabricated with a cladding absorption value of >20dB/m, which is the highest value among LMA step-index fibers with NA<0.06 so far reported to the best of our knowledge. The fabricated Yb-doped fiber was tested in a high-power picosecond amplifier system and enabled the generation of 190 ps laser pulses with a 101 µJ pulse energy and 0.5 MW peak power at an average power of 150 W.