Capacitated Network Research Articles

Full-response model of transient heat transfer of building walls using thermoelectric analogy method

The modeling calculation of heat transfer based on a resistance and capacitance network in building systems is relatively complex. In this study, a full-response model of the thermal circuit transient analysis of wall heat transfer was established based on the thermoelectric analogy mechanism and the transient analysis principle of circuits. The full-response model of wall heat transfer was validated through comparison with experimental results. From the seventh day, the temperatures of the middle and inner surfaces of the wall exhibited significant attenuation and lag compared to the outer surface temperature of the wall. In the same structure and direction, the lag times of the temperatures of inner and outer surfaces of the south walls of the bedroom and study room were 3 h and 9h30min, and the decay temperatures were 5.5 °C and 5.3 °C, respectively. The proposed model improves the adaptability of the thermoelectric analogy resistance and capacitance (RC) network model and shortens the calculation time, providing a theoretical basis for research on multisystem heat transfer.

Study of RF Stray Currents in ITER Neutral Beam Test Facilities

The operation of SPIDER (Source for the Production of Ions of Deuterium Extracted from Radio-frequency plasma), full-scale prototype of ITER NBI (Neutral Beam Injector) radio-frequency ion source, pointed out deleterious effects caused by stray Radio-Frequency (RF) currents flowing in the electrical equipment not included in the RF power system. MITICA (Megavolt ITER Injector and Concept Advancement), the full-scale prototype of ITER NBI, is characterized by a similar design in terms of layout of the power supplies and connections to the beam source; thus, it is expected to be subject to the RF stray currents problem. SPIDER RF system is composed of four RF generators, four coaxial lines and four RF loads. Each RF generator is rated for operation at 200 kW in the frequency range 0.9 ÷ 1.1 MHz. The power is delivered to the four loads via as many RF coaxial lines, housed inside a multiconductor transmission line. Each load consists of a capacitive matching network and two plasma drivers in series. Due to the presence of stray connections at the generator and beam-source side (e.g., parasitic capacitances), unwanted RF currents can flow through alternative paths and negatively affect the components not intended for transmission of RF power, the output stages of power supplies and several diagnostics installed in the High-Voltage Deck (HVD) and at the beam source. This paper presents the development of a circuital model used to estimate the RF stray currents in SPIDER electrical system; the understanding of this phenomenon and the development of a model with predictive capabilities is fundamental for the assessment of the performance of both SPIDER and MITICA and, in general, of alternative RF system layouts with respect to the stray currents issue.

Joint optimisation of transfer location and capacity for a capacitated multimodal transport network with elastic demand: a bi-level programming model and paradoxes

With the growing attention toward developing a multimodal transport system to enhance urban mobility, there is an increasing need to construct new infrastructures, rebuild or expand the existing ones, to accommodate the current and newly generated travel demand. Therefore, this study develops a bi-level model that simultaneously determines the location and capacity of the transfer infrastructure to be built considering the elastic demand in a multimodal transport network. The upper-level problem is formulated as a mixed-integer linear programming problem, whereas the lower-level problem is a combined trip distribution/modal split/assignment model that depicts both the destination and route choices of travellers via a multinomial logit model. Numerical studies are conducted to demonstrate the occurrence of two Braess-like paradox phenomena in a multimodal transport network. The first one states that under fixed demand, constructing new parking spaces to provide the usage of park-and-ride services could deteriorate the system performance measured by the total passengers’ travel time, while the second one reveals that under elastic demand, increasing the parking capacity for park-and-ride services to promote its usage may fail, which would be represented by the decline in their modal share. Meanwhile, a numerical example also suggests that constructing transfer infrastructures at distributed stations outperforms building a large transfer centre in terms of attracting travellers using sustainable transit modes.

Misalignment-Tolerant Series Hybrid with Active Adjustable Constant Current and Constant Voltage Output Wireless Charging System

This paper presents a series hybrid wireless charging system with an active adjustable circuitry offering constant current and constant voltage output characteristics. The series hybrid system consists of the inductor–capacitor–capacitor (LCC) and series-series (SS) networks are used for improving charging pad misalignment tolerance. An active switch is employed to provide an adjustable CC and CV output for different battery charging stages. To demonstrate the performance of the proposed method, a 310 W prototype was built. A systematic optimization in the parameter of the proposed topology to achieve relative constant output was analyzed within a certain range of the designed operating region. The experimental results indicate that the output current fluctuation is less than 5% with load variations, and the output voltage fluctuation is less than 5% with load varying from 19 to 70 Ω, as the pick-up pads misaligned within 50% of the pad outer diameter.

A Novel Key Generation Method for Group-Based Physically Unclonable Function Designs

In recent years, physically unclonable functions (PUFs) have gained significant attraction in IoT security applications, such as cryptographic key generation and entity authentication. PUFs extract the uncontrollable production characteristics of different devices to generate unique fingerprints for security applications. When generating PUF-based secret keys, the reliability and entropy of the keys are vital factors. This study proposes a novel method for generating PUF-based keys from a set of measurements. Firstly, it formulates the group-based key generation problem as an optimization problem and solves it using integer linear programming (ILP), which guarantees finding the optimum solution. Then, a novel scheme for the extraction of keys from groups is proposed, which we call positioning syndrome coding (PSC). The use of ILP as well as the introduction of PSC facilitates the generation of high-entropy keys with low error correction costs. These new methods have been tested by applying them on the output of a capacitor network PUF. The results confirm the application of ILP and PSC in generating high-quality keys.

Modeling of a tunable memory device made with a double-gate MoS2 FET and graphene floating gate

Electronic devices comprising low-temperature processed 2D materials can be utilized in back-end-of-line nonvolatile memory and logic applications, to augment conventional silicon technology. A promising structure for a low-temperature processed digital nonvolatile flash memory device and/or logic device is the double-gate MoS2 FET with a graphene floating gate and a thin h-BN gate dielectric serving as a tunneling dielectric. In this work, we show that experimental hysteretic current–voltage characteristics of this digital flash memory device can be well fit by a simple and effective physics-based model using a WKB approximation to calculate the tunneling current to the graphene floating gate and a capacitive network with 2D density-of-states to calculate the channel current flowing in the MoS2 channel. Accordingly, the model allows a device designer to predict and/or tune characteristics for this memory device, e.g., the width and center-position of the hysteresis loop as well as the value of source–drain current, as a function of both the bottom (control) gate and top (FET) gate voltages. It is noted that shifting of the center-position of the hysteresis loop enables improved reliability and functionality of the memory device in circuit applications and is a unique feature of this double-gated MoS2 FET. Overall, the demonstrated ability to well model this memory device lends further credence that 2D devices could augment silicon technology.

Negative imaginariness and positive realness analysis of state-space symmetric systems with interval uncertainty

In this article, the state-space symmetric systems with symmetrical interval uncertainty that have positive real and negative imaginary properties are studied. First, a necessary and sufficient test in view of a state matrix is derived for a state-space symmetric system to be negative imaginary, which allows having poles at the origin. Second, bounds on symmetrical interval uncertainty that guarantee the positive realness and negative imaginariness of state-space symmetric systems are provided. Finally, the main results are illustrated by a resistor–capacitor network and a numerical design example.

Novel gate air cavity GaN HEMTs design for improved RF and DC performance

Studies are performed to develop physical insights into the RF and DC behavior of GaN HEMTs. In purpose of improving the current gain cutoff frequency (fT) and power gain cutoff frequency (fmax), an air cavity structure was proposed, which efficiently decreases the gate–drain capacitance and gate–source capacitance. As a result, the proposed HEMTs with air cavity offers over 2× improvements in cutoff frequency comparing with the design without, which increases the fT and fmax to 14.9 GHz and 33.1 GHz, respectively. It breaks through the performance bottleneck limited by the length of gate, realizing a relatively high scaling factor that Lg × fT = 20.86 GHz μm when compared with previous reports. Besides, in order to realize both DC and RF performance improvement we proposed another kind of air cavity design, the fT and fmax can be increased by 82% and 37.6% respectively. The maximum saturation drain current approximately increased by 50%, maximum transconductance (gm, max) raise from 209 to 237 mS/mm and the gate current leakage performance is improved to a certain extent. Furthermore, forth bias sweep C–V (capacitance–voltage) curves and current density are also extracted to discuss the mechanism accompany with the reported physical model, based on which 2 simplified capacitive networks are proposed.

On electrical gates on fungal colony

Mycelium networks are promising substrates for designing unconventional computing devices providing rich topologies and geometries where signals propagate and interact. Fulfilling our long-term objectives of prototyping electrical analog computers from living mycelium networks, including networks hybridised with nanoparticles, we explore the possibility of implementing Boolean logical gates based on electrical properties of fungal colonies. We converted a 3D image-data stack of Aspergillus niger fungal colony to an Euclidean graph and modelled the colony as resistive and capacitive (RC) networks, where electrical parameters of edges were functions of the edges’ lengths. We found that and, or and and-not gates are implementable in RC networks derived from the geometrical structure of the real fungal colony.

Design and application of wireless power transfer using Class-E inverter based on Adaptive Impedance-Matching Network

Class-E inverter, which is assumed as an ideal exciter for wireless power transfer system due to their low power losses and suitability for high-frequency operation, can operate under the proper switching conditions when the distance between the transmitter and the receiver and the load is constant. The change in the distance between the coils or the load value removes the optimum switching conditions and causes high switching losses. This paper describes all design procedures and the inductive coupling wireless power transfer system based on a Class-E inverter used as a coil driver. In case the distance between the coils changes, the optimum switching condition of the Class-E inverter and the impedance matching between the transmitter and receiver have been dynamically sustained with an adaptive capacity array on the transmitter side. The best combination of the array involving a serial/parallel capacitor network is configured using a novel searching algorithm for different coil distances. In addition, this study investigates both coupling efficiency and the efficiency of Class-E inverter that is remarked by a few studies in the existing literature. The developed simulation studies and the laboratory prototype with power of 1 kW demonstrate the providing of the zero voltage-switching requirement for Class-E inverter and the impedance matching of the wireless power transfer system in case of variable coupling coefficient. Therefore, the efficiency of power transfer achieved as 91.13% for the implementation circuit.

An effective kernel search and dynamic programming hybrid heuristic for a multimodal transportation planning problem with order consolidation

We study a realistic capacitated multimodal transportation planning problem (CMTPP) faced by logistics companies when trying to obtain a cost advantage in a competitive market. This problem simultaneously considers limited vehicle numbers and order consolidation. Given a set of origin–destination transportation orders with a time window, solving the CMTPP involves determining the delivery paths of these orders on a capacitated network as well as selecting the transportation modes used on these paths. Without violating time windows and network capacity constraints, all customers’ requests must be satisfied exactly, with minimum overall logistics costs. The CMTPP is formulated as a mixed binary linear program based on which an effective kernel search and dynamic programming hybrid heuristic (HKSDP) is proposed, which repeatedly generates feasible solutions. A column generation approach is also proposed to provide a lower bound for the problem which is then used to evaluate the performance of the proposed heuristics. Numerical experiments for various sizes of random instances (with at most 300 orders in a network and 20 nodes) are conducted. The results demonstrate the effectiveness of column generation in obtaining a tight lower bound as well as the efficiency of the HKSDP in achieving a high-quality near-optimal solution. The average optimality gap is approximately 1.04%. We also provide a practical application of the proposed HKSDP to a logistics network in inland China.

Battery Charger Utilizing Coupled Inductor Based High Gain Bidirectional DC-DC Converter: Analysis, Design, and Implementation

The bidirectional dc-dc converter with high voltage gain and high efficiency plays an important role in the designing of battery charging systems. In this paper, design and development of a battery charging system utilizing coupled inductor based high gain dc-dc converter is presented. The converter uses a clamp capacitor network to recover the leakage energy of a coupled inductor. The converter has inherent soft-switching capability during turn ON, which ensures high efficiency at high switching frequency. Design equations to derive value of different passive components are given and a step-wise exclusive design to construct coupled inductor is presented. A 50 kHz, 500 W laboratory prototype has been designed, which can increase the voltage with 10 gain (boost operation) in one direction and can reduce the voltage at (1/10) gain (buck operation) in other direction. The CCCV battery charging algorithm is implemented using generic ARM Cortex-M4 microcontroller. Extensive experiments have been performed and the experimental results are presented in buck, boost, and battery charging operations.

The analysis of charge transport mechanism in mixed ionic electronic conductor composite of Sr2TiCoO6 double perovskite with yttria stabilized zirconia

In this investigation, the ionic conduction mechanism in mixed ionic electronic conductors composites of Sr2TiCoO6/YSZ has been studied with the help of universal dynamic response. 3 mol% and 8 mol% yttria stabilized ZrO2 have been mixed with Sr2TiCoO6 (STC) double perovskite in 1:1 ratio to prepare STC/3YSZ and STC/8YSZ composites via solid-state reaction route. AC Impedance spectroscopy has been carried out to examine the charge transport mechanism, which has been modeled using the microstructural networks of resistors and capacitors. Grain boundaries are more resistive and capacitive compared to the bulk. Modulus spectroscopy analysis demonstrates the non-Debye character of conductivity relaxation with frequency. Complex frequency-dependent AC conductivity is found to obey Almond West power law and reveals that ion migration occurs through the correlated hopping mechanism. Further, the DC conductivity and relaxation time have been found to follow the Barton Nakajima and Namikawa relation, which is correlated with AC to DC conduction. The time-temperature superposition principle has been used to explain the conductivity scaling in the intermediate frequency range. At low temperatures, the ions are localized in the asymmetric potential well, while at high temperatures, hopping behavior starts dominating. Further Kramers–Kronig transformation connects the dielectric strength with conductivity relaxation and verifies the impedance data.

Electrical properties of integrated capacitors made of BST and BCTZ material for impedance adaptation applications

Tunable materials, which exhibit in same time, a non-linear variation of their dielectric permittivity (ɛr) under an external electric field and low dielectric losses, are widely used in electronics for tunable applications. Single capacitors and a network of capacitors and resistors have been manufactured for an exhaustive electric characterization of three paraelectric materials. The first one is a Ba0.55Sr0.45TiO3 (BST) thin film prepared by RF sputtering technique. The second one is a film of Ba0.7Sr0.3TiO3 doped with Cu0.5%Mn1% prepared by using sol-gel processing technique. The third one is a Ba0.94Ca0.06Ti0.84Zr0.16O3 (BCTZ) thin film prepared by sol-gel technique. The first electrical parameter extracted is the breakdown voltage of the capacitors to define the maximum electric field applicable for the following characterizations. These three films have a high relative permittivity, up to 680 for the BST sputtered, 870 for the BST sol-gel, and 570 for the BCTZ sol-gel. They are also characterized by a very high dielectric tunability with 6.7:1 for the BST sputtered, 9.3:1 for the BST sol-gel and 7.6:1 for the BCTZ sol-gel. The quality factor of these paraelectric films is measured at 150 for the BST sputtered, 140 for the BST sol-gel, and 45 for the BCTZ sol-gel. These very high electrical properties are obtained with no compromise on the capacitor lifetime. In conclusion, these three paraelectric films could be used and the choice of either films is driven by which parameters would be the most important in the targeted tunable application.

Method for integrating classical and network reliability: A time varying network reliability evaluation

AbstractMany capacitated flow network papers treat reliability as a time‐invariant property. However, network components degrade over time suggesting that methods to quantify the time‐varying reliability of a network are appropriate. This paper proposes a method to compute the reliability of a multistate capacitated flow network in terms of multistate components characterized by a life distribution. The approach enables the calculation of the probability that demand can be satisfied over period of time despite component degradation. Examples are provided to clarify the steps required and to illustrate the assessments enabled. Based on the classical reliability theory, the Weibull reliability function is employed to characterize the degradation of network components. However, the approach is general and other distributions are also possible. The results indicate that the approach can assist a network supervisor determine reasonable demand rate and time constraint to satisfy demand as well as reason about alternative reliability improvement strategies.

The multi-commodity network flow problem with soft transit time constraints: Application to liner shipping

The multi-commodity network flow problem (MCNF) consists in routing a set of commodities through a capacitated network at minimum cost and is relevant for routing containers in liner shipping networks. As commodity transit times are often a critical factor, the literature has introduced hard limits on commodity transit times. In practical contexts, however, these hard limits may fail to provide sufficient flexibility since routes with even tiny delays would be discarded. Motivated by a major liner shipping operator, we study an MCNF generalization where transit time restrictions are modeled as soft constraints, in which delays are discouraged using penalty functions of transit time. Similarly, early commodity arrivals can receive a discount in cost. We derive properties that distinguish this model from other MCNF variants and adapt a column generation procedure to efficiently solve it. Extensive numerical experiments conducted on realistic liner shipping instances reveal that the explicit consideration of penalty functions can lead to significant cost reductions compared to hard transit time deadlines. Moreover, the penalties can be used to steer the flow towards slower or faster configurations, resulting in a potential increase in operational costs, which generates a trade-off that we quantify under varying penalty functions.

An Improved Comparator Based on Current Reuse and a New Frequency Compensation Technique used in an OTA for Pipeline ADCs

In this paper, a comparator and an operational amplifier considered as essential components, constituting a 10-bit 50-MHz pipeline Analog-to-Digital Converter for Wireless Local Area Network (WLAN) applications, are described and designed. All post-layout and Monte-Carlo simulations, using a 0.35[Formula: see text][Formula: see text]m CMOS AMS process technology with [Formula: see text][Formula: see text]V supply voltage and an input common-mode range of [Formula: see text][Formula: see text]V, are achieved. An improved clocked comparator with a dynamic latch, based on a switched capacitor network, using the current reuse technique for slew rate enhancement and positive feedback for offset voltage compensation, is presented. The operational amplifier, consisting of a fully differential folded cascode operational transconductance amplifier, providing high-gain and good stability, is exhibited. A new frequency compensation technique, based on active resistors, is used to improve amplifier phase-margin. The Monte-Carlo performance results of the designed clocked comparator provide an offset voltage of [Formula: see text][Formula: see text]mV with [Formula: see text][Formula: see text]mV 3[Formula: see text] deviation, a slew rate of [Formula: see text]V/ns with [Formula: see text]V/ns 3[Formula: see text] deviation, and a propagation delay of [Formula: see text][Formula: see text]ns with [Formula: see text][Formula: see text]ns 3[Formula: see text] deviation. Monte-Carlo performance results of the designed operational amplifier provide a phase-margin of [Formula: see text], and a high-gain of [Formula: see text]dB with [Formula: see text] and [Formula: see text]dB 3[Formula: see text], respectively, by using [Formula: see text] load capacitance.

Framework for optimization of long-term, multi-period investment planning of integrated urban energy systems

In order to achieve stringent greenhouse gas emission reductions, a transition of our entire energy system from fossil to renewable resources needs to be designed. Such an energy transition brings two main challenges: most renewables generate variable electric energy, yet most demand is currently not electric (carrier mismatch) and does not always manifest at the same time as supply (temporal mismatch). Integrating multiple energy infrastructures can address both challenges by using the synergy between different energy carriers; building on existing infrastructure, while allowing a robust and flexible integration of the new.This paper proposes an optimization framework for long-term, multi-period investment planning of urban energy systems in an integrated manner. We formulate it as a mixed-integer linear program, combining a capacitated facility location with a multi-dimensional, capacitated network design problem. It includes generation and network expansion planning as well as interconnections between networks and storage infrastructure for each energy system. It can incorporate pathway effects like techno-economic developments, policy measures, and weather variations. The intended use is to support urban decision makers with long-term investment planning, though it can be tailored to fit other geographical or temporal scales.We demonstrate the model using two cases based on an average city in The Netherlands, which wants to reduce its CO2-emissions with 95% by 2050. In the first case, we include explicit carbon-emission constraints to study the effects of the carrier mismatch. In the second case, we implement interannual weather variations to analyze the temporal mismatch. The results give valuable insights into the energy transition design strategy for urban decision makers. They also show the future potential, as well as the computational challenges of the optimization framework.

Optimization of distributed generation units in reactive power compensated reconfigured distribution network

Capacitor Allocation (CA) and Network Reconfiguration (NR) are the traditional methods extensively applied by the researchers for power loss reduction and node voltage improvement in radial Distribution Network (DN) for the past four decades. In recent years, simultaneous optimization of CA and NR is considered to maximize the power loss reduction in a proficient manner in comparison to individual optimization of CA and NR. To solve the objective functions, this work proposes an application of Autonomous Group Particle Swarm Optimization (AGPSO) by optimal allocation and sizing of capacitors with and without NR, under four different cases, subject to satisfying operating constraints. In addition, to ascertain the impact of real power injection on further power loss reduction, this work considers placement and sizing of Distributed Generation (DG) units from single to three optimal nodes in capacitive compensated optimal DN. This proposed methodology is demonstrated using standard IEEE 33 and 69 bus test system and the results obtained by each test case have been compared with other optimization techniques. A significant amount of power loss gets minimized after optimal DG allocation in reactive power compensated optimal DN.

Calculations of Capacitive Take-off Power (CTP) from High Voltage Transmission Lines.(Dept.E)

This paper presents the constructions of capacitive take-off power (ctp) networks in different countries .Also, this paper illustrates the effect of switches on the stability of the network he station antena is built by connecting capacitive part of networks consisting of some condensers in specific arrangement-This arrangement Of each type has series of specific singularities. The presented analysis of uses a technique that divides the problem into two parts; firstly, the capacitive condengers and reactors selection calculations; secondary, calculation of take-off power antena. Also, lt presents a mathematical modelling of the transient processes in a capacitive take- off power network. This model is based on the calculation of magnetic flux of a single -phase two-winding transformer. This model is represented by non-linear equations. The short circuit occurs along the steel core and the leakage flux coupling the separated coils closes out the side of core. The mathematical model is developed to investigate the conditions of transient process analysis in a capacitive take-off power network. The reduction of overvoltage during short circuit period is also studied in this paper. Also, this paper suggests the solution algorithm using programme techniques. The final results and conclusions are presents.