Optimal Gate Research Articles

A Passenger-Centric Model for Reducing Missed Connections at Low Cost Airports With Gates Reassignment

Low cost carriers usually operate from no-frills budget terminals which are designed for quick aircraft turnaround, faster passenger connections with minimal inter-gate passenger transfer times. Such operations are highly sensitive to factors such as aircraft delays, turnaround time and flight connection time and may lead to missed connections for self-connecting transfer passengers. In this paper, we propose a passenger-centric model to analyze the effect of turnaround times, minimum connection times and stochastic delays on missed connections of self-connecting passengers. We use Singapore Changi International Airport Terminal 4, which mainly caters to budget/low cost carriers, as a case study to demonstrate the impact of operational uncertainties on these passenger connections, considering an optimal gate assignment by using heuristic search for scheduled arrivals. The proposed model also incorporates reassignment of gates in the disrupted scenario to minimize spatial deviation from the optimized gate assignments. Results show that the chances of missed connections can be significantly reduced by operationally maintaining higher turnaround time and minimum connection time and by bringing down delays at the airport. Specifically, by maintaining the flight turnaround time at 50 min, minimum connection time at 60 min and by containing arrival delays within 70% of the current delay spread at Terminal 4, transfer passenger missed connections can be prevented for almost all the flights. The gate assignment method adopted in this study is generic and may help to identify the gates, which are more prone to missed connections given operational uncertainties under different flight scenarios.

Optimal Gating System Design of Steel Casting by Fruit Fly Optimization Algorithm Based on Casting Simulation Technology

Casting simulation technology is an effective method to provide the predicted information on defects such as shrinkage, gas entrapment, cold shut, misrun and inclusions. To extend the analysis of casting simulation technology, a new optimal method for gating system design by fruit fly optimization algorithm (FOA) is proposed in this paper. First, according to the filling principles of steel casting, the gating system geometry mathematical model, which includes objective function and constraint conditions, is established. Second, in order to obtain optimal solution, fruit fly optimization algorithm is introduced to solve the above model. Finally, numerical simulation software is used to verify the validity of the proposed optimal method. Taking an upper center plate casting as an example, the results indicate that the proposed optimal method could provide practical and useful suggestions for the designer to obtain higher-quality and lower-resource-cost designs in the gating system design process.

Achieving high gating performance for ion mobility spectrometry by manipulating ion swarm spatiotemporal behaviors in the vicinity of ion shutter

Ion shutter is one of the key components of the drift-tube types of ion mobility spectrometer, which affects both the resolving power and sensitivity of an ion mobility spectrometer. In this work, a spatiotemporal model was built to understand the behaviors of the ion swarms around the ion shutter. For simplicity, a Tyndall-Powell gate (TPG) was chosen as the gating disturbance to the field on the two sides of ion shutter could be separated. It can be inferred from the spatiotemporal model that the ion swarm could be diluted in front of the TPG when the gate closing voltage (GCV) was superposed on the grid facing the ionization region, while it could be compressed behind the TPG when the GCV was superposed on the other grid. These inferences conformed to the narrower and higher ion peaks obtained at GCV superposed on the latter grid and were further verified by the ion distribution profiles obtained at a wide gate opening pulse width. Finally, the product of the resolving power and the gating efficiency was proposed to evaluate the gating performance of an ion shutter. At GCV superposed on the grid facing the drift region, the best gating performance of 42 was obtained with peak height of 1.63 nA and resolving power of 57.2, and was almost twice as high as the optimal gating performance at GCV superposed on the other grid.

Fault Diagnosis in Wind Power System Based on Intelligent Techniques

Wind energy is one of the most important sources as well as being environmentally friendly and sustainable. In this paper, different types of faults of Doubly-Fed Induction Generator (DFIG) have been studied based on Artificial Neural Network (ANN), Particle Swarm Optimization (PSO) and Field Programmable Gate Array. To simulate the wind generators model MATLAB/Simulink program has been used. Artificial Neural Network (ANN) is trained for detection the faults and (PSO) technique is used to get the best weights. After the training process, the network was transformed into a Simulink program and then converted into the Very High Speed Description Language (VHDL) for downloading on the (FPGA) card, which in turn is used to detect and diagnosis the presence of faults where it can be re-programmed with high response and accuracy.

Modelling and Simulation of Doubly-Fed Variable-Speed Pumped Storage Unit

On the basis of the mathematical model of doubly-fed variable speed pumped storage unit, the paper proposes a coordinated control strategy between the AC excitation system and governor. Based on the operation curve of pump-turbine, the optimal speed and gate opening of doubly-fed variable speed pumped storage unit are determined by active power command and real time water head. Simultaneously, the method taking into account of active power command and frequency fluctuation will make doubly-fed variable speed pumped storage unit to automatic regulate the frequency rapidly. Finally, the doubly-fed variable speed pumped storage unit is simulated by Real Time Digital Simulator (RTDS) software under the generating and pumping mode to validate and analyse the operational characteristics and performance.

An optimal low power digital controller for portable solar applications

The design of controllers for solar energy harvesting systems plays the key role in deciding the efficiency of the energy utilized. In applications of energy scavenging, the harvested power is consumed for about 70% in the operation of the converter and controller blocks before being supplied to the load. The proposed optimal Field Programmable Gate Array based Load Predictive Maximum Power Point Tracking (LP_MPPT) Digital Controller is used for low power, speedy, and decisive energy scavenging systems for a long run in applications of wireless or remote sensing or portable. LP_MPPT helps to predict the need of the load and generate the converter output as buck/boost/buck_boost mode power in comparison to the input from solar panels for every clock cycle. The power consumption of the controller section is comparatively reduced as the buck_boost mode of operation utilizes the no operation state. The proposed methodology is simulated and implemented using Xilinx ISE Design Suite 12.1 which is supported by the family SPARTAN 3E. The simulation results thus obtained show an increase in efficiency (94.3%) with trade off factors, namely, speed and area.

Abstract 3050: Imaging tissue extracellular pH for the differential diagnosis of coccidioidomycosis and lung cancer

Abstract Introduction: Our objective was to determine whether acidoCEST MRI—a novel, non-invasive MRI method that measures extracellular pH (pHe)—can differentiate between lung tumors and coccidioidomycosis (valley fever) granulomas within in vivo mouse models of lung cancer and valley fever. Methods: To develop a spontaneous murine lung tumor model, A/J mice received orthotopic injections of urethane to induce formation of lung adenocarcinomas. The Valley Fever Center for Excellence at the University of Arizona infected SW mice with a BSL 2-compatible mutant Coccidioides strain, Δcps1, to develop our preclinical valley fever model. All scans were performed with a Bruker BioSpin 7T MRI system. For all MRI scans, mice were anesthetized with 2.0% isofluorane, respiration and body temperature were monitoreduring scans, and body temperature was maintained at 37 °C. Respiration-triggering (gating) was used in all imaging sequences to compensate for motion artifacts in the lung. For optimal gating, the mouse's respiration rate was maintained at < 50 breaths per minute. Each mouse was scanned with acidoCEST MRI using 370 mg/mL Iopamidol (200 μL IV bolus, 400 μL/hr IV infusion). AcidoCEST MRI (3.5 μT, 300 ms imaging time, 6000 ms presaturation pulse) was performed according to previously published methods, updated with improved respiration gating. For acidoCEST MRI, the saturation pulse continued until terminated by the gating trigger. Spatial pHe maps of tumor and granuloma ROI were produced using Bloch fitting in Matlab 2014a. Average lesion pHe and iopamidol concentration we also recorded. Results: AcidoCEST MRI was successfully applied to the in vivo imaging of murine lung tumors and coccidioidomycosis granulomas. Lung tumors demonstrated successful uptake of the iopamidol contrast agent, with an average concentration of approximately 40 mM. pHe values in the tumor ROI ranged from 6.5 to 7.2 with an average value of 6.64. Granulomas demonstrated successful uptake of iopamidol with an average concentration of about 75 mM. pHe values in granulomas ranged from 7.2 to 7.4 with an average value of 7.29. Conclusion: AcidoCEST MRI may be used to quantify the pHe of murine lung tumors and coccidioidomycosis granulomas in vivo. Our results show that pHe is a promising biomarker for the differential diagnosis of coccidioidomycosis and lung cancer. Citation Format: Leila Renee Lindeman, Edward A. Randtke, Lisa F. Shubitz, Christine M. Howison, Kyle M. Jones, Mark D. Pagel. Imaging tissue extracellular pH for the differential diagnosis of coccidioidomycosis and lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3050.

Fermi-Level-Controlled Semiconducting-Separated Carbon Nanotube Films for Flexible Terahertz Imagers

Carbon-nanotube-related (CNT-related) materials and structures are highly anticipated as potential building blocks for future flexible electronics and photonics. Despite the various promising applications of CNT-related materials, one obstacle is the lack of ability to globally control and tune the Fermi level of microscale-thick CNT films because these films require a certain thickness to maintain their free-standing shape and freely bendable flexibility. In this work, we report on Fermi-level-controlled flexible and bendable terahertz (THz) imagers with chemically adjustable Fermi-level-tuning methods for CNT films. By utilizing the electronic-double-layer technique with ionic liquids, we obtained an on/off resistance ratio (2758) for a semiconducting-separated CNT film with a thickness of 30 μm and tuned the Fermi level at an optimal gate voltage to maximize the THz detector performance. In addition, the development of a gate-free tunable doping technology based on a variable-concentration dopant solut...

Optimal Gate Commutated Thyristor Design for Bi-Mode Gate Commutated Thyristors Underpinning High, Temperature Independent, Current Controllability

The bi-mode gate commutated thyristor (GCT) is an advanced reverse conducting device aiming high-power applications. Due to the high degree of interdigitation of diode parts and GCT parts, it is necessary to investigate how to best separate the two and at the same time, how to maximize the individual power handling capability. This work underpins the latter, for the GCT part. In achieving that, this letter details the optimization direction, identifies the design parameters that influence the maximum controllable current (MCC), and thereafter introduces a new design attribute, the “p-zone.” This new design not only improves the MCC at high temperature but also at low temperature, yielding temperature independent current handling capability and at least 1000 A, or 23.5% of improvement compared to the state-of-the-art. As a result, the proposed design constitutes an enabler for optimally designed bi-mode devices rated at least 5000 A for applications with the highest power requirement.

Gate length scaling optimization of FinFETs

This paper introduces a device performance optimization approach for the FinFET through optimization of the gate length. As a result of reducing the gate length, the leakage current (I[Formula: see text]) increases, and consequently, the stress along the channel enhances which leads to an increase in the drive current (I[Formula: see text]) of the PMOS. In order to sustain I[Formula: see text], work function is adjusted to offset the effect of the increased stress. Changing the gate length of the transistor yields different drive currents when the leakage current is fixed by adjusting the work function. For a given device, an optimal gate length is found to provide the highest drive current. As an example, for a standard performance device with I[Formula: see text] = 1 nA/um, the best performance I[Formula: see text] = 856 uA/um is at L = 34 nm for 14 nm FinFET and I[Formula: see text] = 1130 uA/um at L = 21 nm for 7 nm FinFET. A 7 nm FinFET will exhibit performance boost of 32% comparing with 14 nm FinFET. However, applying the same method to a 5 nm FinFET, the performance boosting is out of expectance comparing to the 7 nm FinFET, which is due to the severe short-channel-effect and the exhausted channel stress in the FinFET.

Ad-Blockers: A Blessing or a Curse?

Users who have an ad-blocker installed present a genuine predicament for a website (a.k.a. publisher): On the one hand, these users do not generate revenue for the website; on the other hand, denying them access can shrink the user base and adversely affect the popularity of the website, ultimately reducing traffic over the long run. This has led some websites to require that ad-block users “white-list” them for obtaining access to an “ad-light” experience. We model the decision problem for a website facing two user segments: regular users and ad-block users. The first-level decision or gating strategy is whether to allow ad-free access to ad-block users or require them to white-list the website for gaining access. When ad-block users are allowed ad-free access, the second-level decision is the level of advertising (or ad intensity) for regular users. When ad-block users are required to white-list, the second-level decisions are the ad-intensities for regular users and ad-block users. The net utility of a user from visiting the website depends on the intrinsic value of the website’s content, the value obtained due to network effects driven by the amount of traffic/popularity of the website, and the cost incurred due to the presence of ads. We derive an optimal gating and ad-intensity strategy for the website and also solve an identical model for a world without ad-block software. We show that the website can increase its revenue by discriminating between regular and ad-block users via the ad-intensities shown to them. More interestingly, we find that the discriminatory power bestowed on the website by ad-blockers can also benefit its users when their outside option is not very attractive. Thus, the advent of ad-blockers can lead to a win-win for both the website and its users. Finally, we propose a superior selective-gating strategy in which only a fraction of ad-block users are gated. We establish the robustness of our conclusions under several enhancements to our base setting: (a) heterogeneous profitabilities from regular users and ad-block users, (b) endogenous adoption of ad-blockers, (c) the presence of a subscription option, and (d) negative externality due to increased traffic. Our analysis ends with recommendations for three stakeholders in this problem, namely, publishers, web-browser developers, and policy makers.

Computational logic with square rings of nanomagnets

Nanomagnets are a promising low-power alternative to traditional computing. However, the successful implementation of nanomagnets in logic gates has been hindered so far by a lack of reliability. Here, we present a novel design with dipolar-coupled nanomagnets arranged on a square lattice to (i) support transfer of information and (ii) perform logic operations. We introduce a thermal protocol, using thermally active nanomagnets as a means to perform computation. Within this scheme, the nanomagnets are initialized by a global magnetic field and thermally relax on raising the temperature with a resistive heater. We demonstrate error-free transfer of information in chains of up to 19 square rings and we show a high level of reliability with successful gate operations of ∼94% across more than 2000 logic gates. Finally, we present a functionally complete prototype NAND/NOR logic gate that could be implemented for advanced logic operations. Here we support our experiments with simulations of the thermally averaged output and determine the optimal gate parameters. Our approach provides a new pathway to a long standing problem concerning reliability in the use of nanomagnets for computation.

Monolithic acoustic graphene transistors based on lithium niobate thin film

This paper introduces an on-chip acoustic graphene transistor based on lithium niobate thin film. The graphene transistor is embedded in a microelectromechanical systems (MEMS) acoustic wave device, and surface acoustic waves generated by the resonator induce a macroscopic current in the graphene due to the acousto-electric (AE) effect. The acoustic resonator and the graphene share the lithium niobate film, and a gate voltage is applied through the back side of the silicon substrate. The AE current induced by the Rayleigh and Sezawa modes was investigated, and the transistor outputs a larger current in the Rayleigh mode because of a larger coupling to velocity ratio. The output current increases linearly with the input radiofrequency power and can be effectively modulated by the gate voltage. The acoustic graphene transistor realized a five-fold enhancement in the output current at an optimum gate voltage, outperforming its counterpart with a DC input. The acoustic graphene transistor demonstrates a paradigm for more-than-Moore technology. By combining the benefits of MEMS and graphene circuits, it opens an avenue for various system-on-chip applications.

Loss analysis and optimum design of a highly efficient and compact CMOS DC–DC converter with novel transistor layout using 60 nm multipillar-type vertical body channel MOSFET

In this paper, we present a novel transistor layout of multi pillar-type vertical body-channel (BC) MOSFET for cascode power switches for improving the efficiency and compactness of CMOS DC–DC converters. The proposed layout features a stacked and multifingered layout to suppress the loss due to parasitic components such as diffusion resistance and contact resistance. In addition, the loss of each MOSFET, which configures cascode power switches, is analyzed, and it is revealed that the total optimum gate width and loss with the high-side (HS) n-type MOSFET topology are 27 and 16% smaller than those with the HS p-type MOSFET topology, respectively. Moreover, a circuit simulation of 2.0 to 0.8 V, 100 MHz CMOS DC–DC converters with the proposed layout is carried out by using experimentally extracted models of BSIM4 60 nm vertical BC MOSFETs. The peak efficiency of the HS n-type MOSFET converter with the proposed layout is 90.1%, which is 6.0% higher than that with the conventional layout.

Optimal Tracking Gate Based on Hybrid Encoding Genetic Algorithm

Optimal Tracking Gate Based on Hybrid Encoding Genetic Algorithm

Binary Adder Circuits of Asymptotically Minimum Depth, Linear Size, and Fan-Out Two

We consider the problem of constructing fast and small binary adder circuits. Among widely used adders, the Kogge-Stone adder is often considered the fastest, because it computes the carry bits for two n -bit numbers (where n is a power of two) with a depth of 2 log 2 n logic gates, size 4 n log 2 n , and all fan-outs bounded by two. Fan-outs of more than two are disadvantageous in practice, because they lead to the insertion of repeaters for repowering the signal and additional depth in the physical implementation. However, the depth bound of the Kogge-Stone adder is off by a factor of two from the lower bound of log 2 n . Two separate constructions by Brent and Krapchenko achieve this lower bound asymptotically. Brent’s construction gives neither a bound on the fan-out nor the size, while Krapchenko’s adder has linear size, but can have up to linear fan-out. With a fan-out bound of two, neither construction achieves a depth of less than 2 log 2 n . In a further approach, Brent and Kung proposed an adder with linear size and fan-out two but twice the depth of the Kogge-Stone adder. These results are 33–43 years old and no substantial theoretical improvement for has been made since then. In this article, we integrate the individual advantages of all previous adder circuits into a new family of full adders, the first to improve on the depth bound of 2 log 2 n while maintaining a fan-out bound of two. Our adders achieve an asymptotically optimum logic gate depth of log 2 n + o (log 2 n ) and linear size O ( n ).

Combining Raman and laser induced breakdown spectroscopy by double pulse lasing.

A new approach combining Raman spectrometry and laser induced breakdown spectrometry (LIBS) within a single laser event was suggested. A pulsed solid state Nd:YAG laser running in double pulse mode (two frequency-doubled sequential nanosecond laser pulses with dozens microseconds delay) was used to combine two spectrometry methods within a single instrument (Raman/LIBS spectrometer). First, a low-energy laser pulse (power density far below ablation threshold) was used for Raman measurements while a second powerful laser pulse created the plasma suitable for LIBS analysis. A short time delay between two successive pulses allows measuring LIBS and Raman spectra at different moments but within a single laser flash-lamp pumping. Principal advantages of the developed instrument include high quality Raman/LIBS spectra acquisition (due to optimal gating for Raman/LIBS independently) and absence of target thermal alteration during Raman measurements. A series of high quality Raman and LIBS spectra were acquired for inorganic salts (gypsum, anhydrite) as well as for pharmaceutical samples (acetylsalicylic acid). To the best of our knowledge, the quantitative analysis feasibility by combined Raman/LIBS instrument was demonstrated for the first time by calibration curves construction for acetylsalicylic acid (Raman) and copper (LIBS) in gypsum matrix. Combining ablation pulses and Raman measurements (LIBS/Raman measurements) within a single instrument makes it an efficient tool for identification of samples hidden by non-transparent covering or performing depth profiling analysis including remote sensing. Graphical abstract Combining Raman and laser induced breakdown spectroscopy by double pulse lasing.

Network traffic flow optimization under performance constraints

In this paper, a model-based perimeter control policy for large-scale urban vehicular networks is proposed. Assuming a homogeneously loaded vehicle network and the existence of a well-posed Network Fundamental Diagram (NFD), we describe a protected network throughout its aggregated dynamics including nonlinear exit flow characteristics. Within this framework of constrained optimal boundary flow gating, two main performance metrics are considered: (a) first, connected to the NFD, the concept of average network travel time and delay as a performance metric is defined; (b) second, at boundaries, we take into account additional external network queue dynamics governed by uncontrolled inflow demands. External queue capacities in terms of finite-link lengths are used as the second performance metric. Hence, the corresponding performance requirement is an upper bound of external queues. While external queues represent vehicles waiting to enter the protected network, internal queue describes the protected network’s aggregated behavior.By controlling the number of vehicles joining the internal queue from the external ones, herewith a network traffic flow maximization solution subject to the internal and external dynamics and their performance constraints is developed. The originally non-convex optimization problem is transformed to a numerically efficiently convex one by relaxing the performance constraints into time-dependent state boundaries. The control solution can be interpreted as a mechanism which transforms the unknown arrival process governing the number of vehicles entering the network to a regulated process, such that prescribed performance requirements on travel time in the network and upper bound on the external queue are satisfied. Comparative numerical simulation studies on a microscopic traffic simulator are carried out to show the benefits of the proposed method.

An Analytical Model for False Turn-On Evaluation of High-Voltage Enhancement-Mode GaN Transistor in Bridge-Leg Configuration

Compared with the state-of-the-art Si-based power devices, enhancement-mode Gallium Nitride (E-mode GaN) transistors have better figures of merit and exhibit great potential in enabling higher switching frequency, higher efficiency, and higher power density for power converters. The bridge-leg configuration circuit, consisting of a controlling switch and a synchronous switch, is a critical component in many power converters. However, owing to the low threshold voltage and fast switching speed, E-mode GaN devices are more prone to false turn-on phenomenon in bridge-leg configuration, leading to undesirable results, such as higher switching loss, circuit oscillation, and shoot through. In order to expand gate terminal's safe operating margin without increasing reverse conduction loss during deadtime, negative gate voltage bias for turn-off and antiparallel diode could be applied to E-mode GaN device. In this paper, with consideration of strong nonlinearities in C–V and I–V characteristics of high-voltage (650 V) E-mode GaN transistors, analytical device models are first developed. Then, we develop an analytical circuit model that combines the circuit parameters with intrinsic characteristics of the high-voltage GaN transistor and antiparallel diode. Thus, key transient waveforms with regard to the false turn-on problem can be acquired, including displacement current and false triggering voltage pulse on gate terminal. The simulated waveforms are then verified on a testing board with GaN-based bridge-leg circuit. In contrast to piecewise switching process models and PSpice simulation, the proposed model exhibits outstanding performances. To provide design guidelines for mitigating false turn-on of GaN transistor, the impacts of different circuit parameters, along with the optimum negative gate voltage bias, are investigated based on the proposed model.

An Accurate Subcircuit Model of SiC Half-Bridge Module for Switching-Loss Optimization

The increasing demand for high power density requires the power converter to operate in high switching frequency. Silicon carbide (SiC) power module is regarded as one of the most promising candidates for high-frequency applications due to the superior switching speed and low switching loss. With the increase of switching frequency, the switching loss will be the limiting factor of efficiency. Hence, it should be minimized during each switching transition. The optimization of switching loss is normally achieved by the repetitive double pulse test experiments. It is time-consuming to find an optimum gate resistance to achieve the tradeoff between switching loss and electromagnetic interface. In this paper, an accurate subcircuit model for SiC power module is proposed to assist optimization of switching loss in converter design. By considering the device physics and structure, an accurate Miller capacitance model is obtained. Moreover, a parameter extraction procedure is presented, which is based on the datasheet. Good agreements are achieved between the PSpice simulation and experiment.