Characteristics Of Individual Devices Research Articles

A spotter's guide to endovascular endograft recognition

Since the first endovascular aneurysm repair of abdominal aortic aneurysms in the 1980s, there has not only been exponential growth of procedures performed per year, but also rapid proliferation of stent grafts. With the resultant growth in revision and explant procedures on these grafts, we developed this guide to aid trainees in surgery and radiology in identifying these grafts. Our goal with this spotter's guide is to allow the identification of key features from commonly implanted devices radiographically, such as points of fixation, radiopaque markers, and stent patterns. The operative approach for the treatment of endograft complications, including endoleak embolization, aortic cuff extension, laser fenestration, limb extension, and endograft explant is often dramatically impacted by the type of endograft and its individual device characteristics. The intent of this guide is to aid practitioners in identifying endovascular aneurysm repair endografts of all ages, even those that have not been implanted in years.

Modeling and digital twin

This article considers various types of modeling and the concept of "digital double", as well as their examples of the concept of implementation. For example, computer simulations not only provide a prediction, but also identify which control effects on the system will lead to favorable developments between the link components of the model. In this case, digital simulation allows to optimize the service sequence of sensor elements SE with its time-bound, ensuring minimization of flight time and unconditional absence of complete battery discharge of any of the sensor elements. In this case, the model interacts with the network being modeled, constantly receiving from it up-to-date information about the state, which is characteristic of digital duplicates. Digital doubles can display not only the characteristics of individual devices, but also process characteristics. Modern production processes are very complex and distributed in space and time. Models of such processes should therefore consider the distributed nature of the modelling objects. The interaction of the digital model with the model object representing the production process is also analyzed. The interaction takes place through integration tools that link the model with the model object.

Predictors of electronic cigarette dependence among non-smoking electronic cigarette users: User behavior and device characteristics

IntroductionECIGs differ in their ability to deliver nicotine to the user and, consequently, they may differ in their ability to produce dependence. This study examined individual device characteristics, device type, and user behaviors as predictors of ECIG dependence in a sample of never-smoking ECIG users. MethodsParticipants (N = 134) completed an online survey that assessed demographics, ECIG use behavior, and ECIG dependence as measured via the Penn State Electronic Nicotine Dependence Index (PSECDI) and E-cigarette Dependence Scale (EDS-4). Participants uploaded a picture of their personal ECIG device/liquid, which was coded by raters to identify product features. Multivariable linear regressions examined device characteristics (e.g., adjustable power, nicotine concentration) and device type (e.g., vape pen, mod, pod, modern disposable) as predictors of dependence controlling for demographics and user behaviors (e.g., ECIG use duration and frequency, other tobacco use). ResultsLonger durations of ECIG use and more use days/week were associated significantly with higher PSECDI (β’s = 0.91 and 1.90, respectively; p’s < 0.01) and EDS-4 scores (β’s = 0.16 and 0.28, respectively; p’s < 0.01). Higher nicotine concentrations were associated with higher PSECDI scores only (β = 0.07, p =.011). Dependence scores did not differ as a function of ECIG device types after controlling for covariates. ConclusionsECIG dependence was observed among the never-smoking ECIG users in this sample, regardless of their ECIG device/liquid features. Findings suggest that regulatory efforts aimed at reducing the dependence potential of ECIGs in never smokers should focus on overall nicotine emissions rather than product features.

GaN-based complementary inverter logic gate using InGaN/GaN superlattice capped enhancement-mode field-effect-transistors

GaN-based high electron mobility transistors (HEMTs) have received much attention due to their potential usage in radio-frequency and high power applications. However, the development of logic gates has remained mostly elusive due to the still challenging reliable operation of the field-effect enhancement-mode n-transistor and nascent stage for the p-transistor. The n-transistor behavior is mainly achieved by combining the aggressive thinning down of the barrier layer, using charged oxides, and p-doping the cap layer. The p-transistor generally requires a heavily doped p-GaN layer. The realization of both transistors on the same substrate remains challenging due to the conflicting requirements for n- and p-transistors. Here, we propose a GaN-based field-effect complementary transistor device using a p-doped InGaN/GaN superlattice (SL) structure on top of the barrier layer of the HEMT heterostructure. The SL structure changes the electrostatics of the heterostructure by the formation of a two-dimensional hole gas region. An undoped SL structure is shown to be enough to lift the conduction band-edge above the Fermi level to convert the n-transistor from depletion-mode (D-mode) to enhancement-mode (E-mode). The lifting of the bands, in turn, creates a natural quantum-well for the holes in the p-transistor. An additional p-doping of the SL moves the threshold voltage of the E-mode n-transistor further into a positive direction and increases the hole density in the quantum-well E-mode p-transistor. The SL structure, which can be grown by a standard epitaxial process, facilitates the realizations of both the n- and p-transistors. The characteristics of individual devices are further analyzed. A digital inverter gate is simulated, and critical static and dynamic performance parameters are reported. The propagation delay indicates that logic operations can be done at a very high speed compared to those offered by other conventional semiconductors.

Tunnel recombination junction influence on the a-Si:H/SHJ tandem solar cell

An effective tunnelling recombination junction (TRJ) is the most important part in a series connected tandem solar cell, and it always plays a significant role to match the current densities of individual solar cells. The aim of this paper is to find a TRJ that shows more efficient ohmic behavior compared to that used in typical thin film tandem solar cells, due to high current nature. Silicon heterojunction (SHJ) based tandem solar cell structure (a-Si:H/SHJ) was studied in detail with simulations using Advanced Semiconductor Analysis (ASA) software. Trap assisted recombination tunnelling and field enhanced mobility mechanisms have been included in our model analysis. Moreover, we also have simulated individual device characteristics of each a-Si:H (n-i-p), SHJ cell (top and bottom subcells of an a-Si:H/SHJ tandem cell), and correlated with the performance of the a-Si:H/SHJ tandem solar cell. The tandem device with a TRJ, the type which used in a thin film silicon tandem cell, shows low open circuit voltage (Voc) = 1.12 V and poor fill factor (FF) = 0.29 with S-shape in light current density–voltage (J-V) characteristics due to charge transport issue at the interface of top and bottom cells. An appropriate TRJ gives efficient recombination and an excellent ohmic contact at the interface between the subcells to match the current of each device. With the implementation of the optimum TRJ at the junction of two cells, Voc and FF have improved significantly to 1.35 V and 0.79 respectively. Also, we observed that the Voc of the tandem solar cell is nearly equal to the sum of the corresponding individual subcells, confirming no trapping related field loss at the junction.

Bias-Dependent Contact Resistance Characterization of Carbon Nanotube FETs

An extraction method for a bias-dependent contact resistance is presented and applied to simulation and experimental data of single and multi-tube carbon nanotube field effect-transistors (CNTFETs) with different channel lengths and Schottky barrier heights. The method relies on the individual device characteristics, i.e., it can be applied to different CNTFET technologies. Furthermore, it does not require the fabrication of test structures or challenging model calibration. The extracted values correspond to reference values in simulations and are as well similar to the ones obtained for the fabricated devices with other more expensive, technology-specific analytical and physics-based approaches. Hence, the extraction method presented here can be considered as an efficient and accurate alternative. By revealing the bias-dependence of the contact parameters, rarely reported in the literature, the nature of the Schottky barriers can be characterized and the contact transparency can de idenitifed.

Investigation of the atmosphere influence on device characteristics and NO2 sensing performance of organic field-effect transistors consisting of polymer bulk heterojunction

Abstract Organic field-effect transistors (OFETs) using polymer as the active layer are being intensively developed for flexible electronics including gas sensor. The strategy of polymer blends comprising semiconducting polymer mixed into an insulating polymer matrix has shown great potential in improving the electrical and sensing performance of OFETs. Herein two semiconducting polymers of poly(3-hexylthiophene-2,5-diyl) (P3HT) and poly(9-vinylcarbazole) (PVK) are used to construct a polymer bulk heterojunction, through exploring the atmosphere influence on device characteristics and NO2 sensing performance of the transistors, an in-depth illumination of the underlying sensing mechanism is carried out. Firstly, by using nitrogen (N2) and dry air as carrier gases, the individual device characteristics and sensing performance under certain NO2 concentrations are investigated. It can be observed that O2 has a greater effect on the electrical performance than other atmospheric components, which is different from the previous report of neat P3HT-based device. Specifically, at the high gate voltage, the response of drain current under N2 is more than 2 times higher than that under dry air, and the mobility variation exhibits a 2-fold enhancement. In contrast, at a low gate voltage (0 V) under dry air, the response is 2-fold greater than under N2. Then, the underlying sensing mechanism of these gas sensors consisting of various P3HT fractions in different operating environment is discussed. Finally, the OFET gas sensor with a high sensitivity to NO2 under dry air is obtained, i.e., the highest current sensitivity is ∼12381% for 15 ppm with 50% P3HT, which is more than 30 times higher than that of pure one. This study on gas sensing mechanism of OFET consisting of semiconducting polymer bulk heterojunction can offer novel inspiration to realize high performance OFET and the corresponding gas sensor.

The pressure reduction coefficient: A new parameter to assess aneurysmal blood stasis induced by flow diverters/disruptors.

Background and purpose Pore density (PD), surface metal coverage (SMC) and the number of wires are all different parameters which can influence the efficacy of a flow disruptor/diverter. Nevertheless, the relative importance of a parameter to induce intra-aneurysmal blood stasis is still poorly evaluated. Therefore, comparison between devices based on a unique value is not reliable. The aim of this study was to propose a new bench top parameter (the pressure reduction coefficient (PRC; ξ)) in order to assess the global haemodynamic effect of each flow diverter/disruptor to slow flow. Methods Eight devices were tested invitro during three different flow conditions. For the eight devices, the PRC was computed at different volumetric flow rates to characterise flow reduction. Comparison was made with SMC, PD and the number of wires. Results The PRC obtained for flow disruptors was on average 1.5 times more efficient in reducing flow compared to flow diverters. PD (mm2) ranged from 24 to 38 for flow diverters and did not independently correlate with the PRC. The SMC of flow diverters ranged from 25% to 70%, and ranged from 20% to 100% for flow disruptors, without independent correlation to the PRC. The number of wires ranged from 48 to 96 for the flow diverters and did not correlate independently to the PRC. Conclusion There were no direct correlations between individual device characteristics and the PRC, suggesting a multifaceted and interrelating association of the overall design of each implant. Hence, the PRC could be used as a simple, reliable parameter to assess the overall capacity of flow disruptors/diverters to induce intra-aneurysmal blood stasis.

Analysing the impact of large-scale decentralised demand side response on frequency stability

Advances in communications technology, higher penetration rates of renewable energy and an evolution towards smarter electrical grids are enabling a greater role from demand side response (DSR) in maintaining power system security and reliability. The provision of primary operating reserve (POR) from domestic loads through a decentralised, system frequency based approach is discussed. By considering a range of system configurations (generation mix, system generation and load) and control strategies, this paper endeavours to answer critical questions concerning the large-scale roll out of decentralised DSR, including the following: what are the implications of DSR resource seasonal variability on system operation and performance following the loss of a large infeed/load? Do increased load coincidence and energy payback phenomena have the potential to significantly impact system frequency recovery? How do DSR controller hardware characteristics influence the provision and effectiveness of reserve delivery? What are the repercussions of a “fit & forget” approach to decentralised control from flexible load on frequency stability as the technology penetration increases? Can DSR be directly substituted for conventional reserve sources while recognising its post-event recovery period? Residential customer behaviour, seasonal effects and the diversity of individual device characteristics are recognised in a detailed thermodynamic flexible load model which is integrated with a detailed power system model to perform the analysis.

Research challenges in digital education.

Simulation and other forms of digital learning will occupy a place of increasing prominence in medical education in the future. However, to maximally use the potential of these media, we must go beyond a research agenda dictated by a ‘Does it work?’ question to one driven by careful analysis of the nature of the task to be learned and its relation to the characteristics of the technology. Secondly, we must change the focus from the characteristics of individual devices to a broader approach to design of a digital curriculum based on current understanding of the nature of human learning.

Uniformity assessment of key characteristics of quantum-dot infrared detectors: A prerequisite for focal plane arrays

We have studied some key characteristics of individual InAs∕GaAs quantum-dot infrared photodetectors in a linear array to assess their suitability for imaging applications. The dark current-voltage characteristics of the devices in the array are almost identical. Furthermore, the low-temperature (78K) photoresponse spectra are nearly identical for all devices. The average peak responsivity was about 1.03A∕W, while the average peak detectivity was about 2.16×109cmHz1∕2∕W. The standard deviations of these two metrics and those of other important parameters were relatively small. Uniformity of individual device characteristics over large arrays is an important prerequisite for high-quality imaging arrays.

COMPARISON OF UNSUPERVISED CLUSTERING METHODS FOR AUTOMATIC ABNORMALITY CLASSIFICATION IN A REMOTELY-MONITORED ARTIFICIAL HEART

Purpose: For remote monitoring of a biventricular assist device, an automatic abnormality detection algorithm that can adaptively correspond to variances in dynamic characteristics of individual devices and unexpected accidental events in use of the devices, has been studied. Unsupervised learning and clustering methods were applied to process the automatic detection of abnormal state and compared. Method: The input pattern for the classification consists of two parameters, the filling volume index and the electrical energy input index that are the most important parameters representing device status. For the unsupervised clustering of the input pattern, Fuzzy C-Means clustering, Gustafson-Kessel method, and the competitive learning artificial neural network method were used. A simple map of abnormality domains was proposed to define clustering goal. The proposed methods were tested on a set of data collected in a 20-day animal experiment in which an actual accidental event with the inflow cannular in early post-op, days was occurred. Results: The Fuzzy C-Means clustering showed best practical results with the good clustering performance and the least calculation time among the three methods.Figure

Resonant-tunneling diode and HEMT logic circuits with multiple thresholds and multilevel output

By using resonant-tunneling diodes (RTDs) and high electron mobility transistors (HEMTs), we implement a new class of logic circuits that operate with multiple thresholds and multilevel output. The basic idea of the circuits is to synthesize transfer characteristics by key logic elements, namely, up and down literals. We first describe two fundamental logic circuits based on this idea: a ternary inverter and a literal gate. Then we present experimental results on these circuits fabricated by integrating InP-based RTDs and HEMTs. It is found that these circuits operate successfully with threshold voltages and output levels that have been predicted from individual device characteristics. Consequently, the validity of the basic idea behind the circuits presented here is proven. The device counts and the number of logic stages required for the present circuits are less than half those for conventional ones. A possible application is finally discussed.

Process Analysis with Nuclear Technique

Experimental determination of response characteristics of individual devices and complete production plants with nuclear technique in different working conditions are discussed. The main principles of the processing of experimental data are described and several examples are presented of measurement from different industrial devices of glass, chemical and pulp industry and of sewage treatment plant

Direct-write metallization of Silicon MOSFET's using laser photodeposition

Gate electrodes of enhancement-mode silicon MOSFET's have been written directly using a new, mask-free laser photodeposition technique. Transistor transconductances and threshold voltages were systematically tuned by varying the gate geometry with the laser beam. The new metallization process is potentially useful for tuning and optimizing the characteristics of individual devices in integrated circuits.

Chemical process analysis with nuclear technique

Nuclear technique is used with advantage for experimental determination of dynamic characteristics of individual devices and complete production plants. The main principles of the processing of experimental data obtained with nuclear technique are described and examples are presented of measurements on industrial devices for oxosynthesis, zinc production, NPK fertilizer and titanium white production.