Minimum Output Research Articles

Design Considerations for Power-Efficient Fully Integrated 3:1 Switched Capacitor DC-DC Converter for PV Modules

This article presents a power-efficient DC-DC converter based on a switched-capacitor (SC) cell in power management systems supplied for fully integrated photovoltaic (PV) modules. These modules shall provide high-performance point-of-load voltage regulation. The primary objective of this study is to better utilize capacitance and switches by selecting a proper SC topology in order to improve the power efficiency of SC converters. A general steady-state performance model is investigated to optimize and compare a variety of SC DC-DC topologies. The investigation method relies on a charge-multiplier approach and considers the impact of area constraint on capacitors. To identify the most suitable topology for a given conversion ratio, the performance-limit metrics of SC converters are calculated. The analysis provides framework to determine optimum switch size and switching frequency for a two-phase 3:1 series–parallel converter for a target load current of 10 mA implemented on a 22 nm process technology. The results shows that a minimum of 250 MHz switching frequency is desirable for achieving a target efficiency greater than 85% while maintaining the minimum output voltage of 0.34 V. The analysis results are verified through MATLAB and PSpice-based simulations.

Metaheuristic optimizing energy recovery from plastic waste in a gasification-based system for waste conversion and management

In an era where sustainable waste management and clean energy production are paramount, this study presents an innovative integration of plastic waste gasification with solid oxide fuel cell (SOFC) technology, optimized through metaheuristic particle swarm optimization (PSO). The research explores the conversion of polypropylene (PP) waste into syngas via gasification, which is then utilized as a fuel for SOFCs to generate electricity. The optimization process focuses on maximizing power and heating outputs while minimizing carbon dioxide emissions. The study's findings demonstrate the potential of integrating gasification and SOFC technologies to create a sustainable energy system that addresses the challenges of plastic waste. Key findings from the metaheuristic PSO multi-objective optimization reveal that optimal power production, approximately 360 kW, is achieved at temperatures exceeding 1140 K, irrespective of the steam/PP waste ratio. Heating production peaks at 1000 kW with temperatures above 1120 K and utilization factors over 0.765, while the minimum heating output is 700 kW. Emission analysis indicates a significant reduction in carbon dioxide emissions with increased temperatures and utilization factors, achieving a minimum of 700 kg/MWh at temperatures above 1120 K. The study's results demonstrate the effectiveness of the PSO optimization in fine-tuning the operational parameters of the integrated system, leading to improved energy efficiency and reduced environmental impact. Power production of 366.37 kW, a significant heating rate of 995.20 g/s, and emissions of 714.06 kg/MWh are the optimum performances. The research provides valuable insights into the potential of plastic waste-to-energy technologies as sustainable solutions for energy production and waste management.

Research on Cascaded On‐Board DC/DC Converter Based on Three‐Phase Interleaved LLC

ABSTRACTThe on‐board DC/DC converter proposed in this research consists of a Buck converter and a three‐phase interleaved LLC resonant converter. This paper analyzes the average current and output current ripple characteristics of the rear‐stage converter in addition to explaining the topology and working principles of the front‐stage Buck converter and the rear‐stage three‐phase interleaved LLC resonant converter. To establish a single‐phase fundamental equivalent circuit for the rear‐stage converter, apply the fundamental wave analysis method, and it is essential for comprehending the impact of relevant system parameters on voltage gain characteristics and resonant operating regions. Conducting research on the two‐stage on‐board DC/DC converter's control strategy involves establishing small‐signal circuit models for both front and rear stage converters, derivation of parameters for double closed‐loop control, and determination of the control strategy employing phase‐shifted current sharing for the rear‐stage converter in cases where significant tolerance exists in resonant components. The simulation for a two‐stage on‐board DC/DC converter results indicates that under various conditions of resonant component tolerance, the converter is capable of achieving balanced phase currents and demonstrates minimal output current ripple prior to capacitor filtering. A 1.5‐kW experimental prototype has been fabricated, and the experimental findings indicate that the output voltage remains stable at 13.8 V despite fluctuations in input voltage. The highest efficiency of the prototype is about 96.27%, and the utilization of phase‐shifting current balancing control results in a notable reduction in output current ripple. This provides more evidence that the design of a two‐stage on‐board DC/DC converter is correct.

Storing electricity in the low-rank coal: The heat-upgrading carnot battery concept and a comprehensive thermodynamic analysis

Promoting the energy/exergy performance of Carnot batteries is beneficial for future applications. This work proposed a Carnot battery concept deeply integrated with the low-rank coal (LRC) power plant (LCPP) for (1) enhancing the energy/exergy performance and (2) reducing LCPP's carbon emission and the minimum technical output (to adopt excess renewable power). The enhancement is attributed to the heat-upgrading effect of LRC pre-drying process and the energy complementarity between the subunits. A thermodynamic model based on the typical LCPP and Carnot battery cases is established to assess and analyze the proposed system. As the results show: (1) Daily average round-trip/exergy efficiencies reach 70.92 % and 54.28 %, and 3.36 % of carbon emission (126.52 ton/day) is reduced in 24 h, significantly higher than the conventional HP-ORC Carnot battery integrated with LCPP. (2) The performance of the proposed Carnot battery cannot be directly predicted from the subunits' performance due to the discharge during the charging periods; however, as long as the integrated charging capacity is not too small, the energy/exergy performance can maintain an elevated level. (3) For a generalized HP-ORC Carnot battery, low exergy input of discharging cycle limits the performance improvement; however, in the proposed system, the energy-upgrading effect compensates for this shortcoming.

New Constructive Counterexamples to Additivity of Minimum Output Rényi p-Entropy of Quantum Channels

New Constructive Counterexamples to Additivity of Minimum Output Rényi <i>p</i>-Entropy of Quantum Channels

DEVELOPMENT OF EFFICIENT AND ENVIRONMENTALLY FRIENDLY SEPTIC TANKS

In many communities in Indonesia, there are still many areas where their homes do not have a toilet (water closet) that meets hygiene and health requirements. This is caused by many factors, including because there are still many people who live below the poverty line, both economically poor and poor in knowledge (human resources). Procurement of toilets (water closets) which also include a septic tank system with a minimum output that is environmentally friendly and of course cost efficient is very necessary to improve public health. Based on the description above, this research was created in order to provide procurement and development of efficient and environmentally friendly septic tanks. This research is very necessary because of the discovery of an efficient alternative material by using used drums which can be used as septic tanks in Lampung, but it has not deepened the issue of waste output that is safe for the environment. This research was carried out using a constructivist qualitative method with assistance from DIGILIB Digital Library &amp; OPAC UB sources. is at Brawijaya University Malang, where the author is registered as a student in the environmental science doctoral program at Brawijaya University Malang.

Conducted interference and voltage ripple suppression study in LLC resonant converter based on symmetric chaotic spread spectrum

ABSTRACT Spread-spectrum modulation technique can effectively reduce the peak value of conducted interference in automotive LLC DC/DC converters, but it will bring more serious ripple problems to Class E resonant converters. In this paper, we investigate the voltage ripple trend of LLC resonant converter when applying spread-spectrum modulation, and propose a chaotic signal sampling rule under the minimum output voltage ripple. A symmetric chaotic spreading method is proposed to reduce the output voltage ripple from the source by changing the distribution sequence of the chaotic signal to make it centrosymmetric. The symmetric chaotic spread spectrum is simulated and analysed to be able to suppress the conduction interference while reducing the voltage ripple, and is verified by experiments. This modulation strategy does not require the addition of auxiliary circuits and additional control links, which saves cost and reduces the difficulty of designing control links.

A CMOS front-end circuit for capacitive sensors with zero adjustment

A front-end circuit with measurement zero adjustment was designed using 180nm CMOS technology for capacitive sensors. A series-switched capacitor composed of capacitor under test and MOSFETs is controlled by a clock signal to convert capacitance to current. The minimum output current at fixed capacitance can be adjusted by applying different voltage to realize zero adjustment. The test shows that the output current has a monotonic linear relationship with the measured capacitance, with capacitance detection range reaches 50pF-3000pF and an output current range of 0.59mA-22.2mA. The maximum span of multiple measurements was lower than 8.37uA. The stable time is less than 23ms and sensitivity is 19.8uA/pF. This circuit is suitable for long-distance and wide-range capacitance detections.

Family Medicine Resident Scholarly Activity Infrastructure, Output, and Dissemination: A CERA Survey.

Meeting scholarly activity requirements continues to be a challenge in many family medicine (FM) residency programs. Studies comprehensively describing FM resident scholarship have been limited. We sought to identify institutional factors associated with increased scholarly output and meeting requirements of the Accreditation Council for Graduate Medical Education (ACGME). Our goals were to: (1) describe scholarly activity experiences among FM residents compared with ACGME requirements; (2) classify experiences by Boyer's domains of scholarship; and (3) associate experiences with residency program characteristics and scholarly activity infrastructure. This was a cross-sectional survey. The survey questions were part of an omnibus survey to FM residency program directors conducted by the Council of Academic Family Medicine Educational Research Alliance (CERA). All ACGME-accredited US FM residency program directors, identified by the Association of Family Medicine Residency Directors, were sampled. Of the 691 eligible program directors, 298 (43%) completed the survey. The respondents reported that 25% or more residents exceeded ACGME minimum output, 17% reported that 25% or more residents published their work, and 50% reported that 25% or more residents delivered conference presentations. Programs exceeding ACGME scholarship requirements exhibit robust infrastructure characterized by access to faculty mentorship, scholarly activity curricula, Institutional Review Board, medical librarian, and statistician. These findings suggest the need for codified ACGME requirements for scholarly activity infrastructure to ensure access to resources in FM residency programs. By fostering FM resident engagement in scholarly activity, programs help to create a culture of inquiry, and address discrepancies in funding and output among FM residency programs.

Exploring the Consumption Pattern of Millets among Rural Women of Udham Singh Nagar District of Uttarakhand, India

The cultural traditions and customs of the rural communities are profoundly ingrained with the production and diverse uses as well as benefits of millets. The production of millets follows the principle of minimum input and maximum output and known as poor men’s food. Therefore, present study was conceptualized with main objective to know the consumption pattern and knowledge related to millet among rural women. Hence, in-person interviews were conducted among 120 rural women of Pantnagar, Uttarakhand. Majority of rural women (48%) were young (&lt; 27 years of age), educated and had nuclear family (68%). They reported that Ragi (32%), Bajra (25%), Jowar (22%), Chaulai (16%) and Jhangora (5%) were highly consumed millets among them. Majority preferred to make chapatti of millet flour and that to only during winter season. They also liked to eat millets as whole grain (81.9%) and in puffed form (20.48%). Further, study revealed that more than half percent had poor knowledge about environmental benefits and consumption benefits of millets. The study suggested that more small steps should be taken to disseminate accurate knowledge and conduct demonstration sessions in communities to promote the millet consumption and production as well.

Investigating the impact of cavity parameters on an ultrashort pulse in a fiber laser

Fiber lasers have numerous applications in various fields due to their compact design, low noise levels, high efficiency, and robust stability. We present a study focusing on the impact of cavity parameters on ultrashort pulses in fiber lasers, proposing an ultrafast laser that utilizes a MoTe2 saturable absorber (SA). Here numerical simulations allowed us to analyze the diverse pulse dynamics within a laser cavity, incorporating a SA, a segment of passive fiber, and erbium-doped fiber (EDF). Key factors of second-order dispersion, nonlinearity, gain saturation energy, small signal gain coefficient, and modulation depth and saturable energy of the SA were simulated. According to the simulations, we obtained the parameter settings for the minimum output pulse duration using a neural network and genetic algorithm. Then we proposed a normal dispersion laser with a MoTe2 mode-locker, capable of emitting dissipative soliton with a pulse duration of 824 fs and a spectrum bandwidth of 13.2 nm. These simulations provide valuable guidance for the design and optimization of fiber lasers, presenting a versatile and practical approach for applications.

A 0.055 mm2 Total Area Triple-Loop Wideband Fractional-N All-Digital Phase-Locked Loop Architecture for 1.9–6.1 GHz Frequency Tuning

This paper presents a wideband fractional-N all-digital phase-locked loop (WBPLL) architecture featuring a triple-loop configuration capable of tuning frequencies from 1.9 to 6.1 GHz. The first and second loops, automatic frequency control (AFC) and counter-assisted phase-locked loop (CAPLL), respectively, perform coarse locking, while the third loop employs a digital sub-sampling architecture without a frequency divider for fine locking. In this third loop, fractional-N frequency synthesis is achieved using a delta-sigma modulator (DSM) and digital-to-time converter (DTC). To minimize area, digital modules such as counters, comparators, and differentiators used in the AFC and CAPLL loops are reused. Furthermore, a moving average filter (MAF) is employed to reduce the frequency overlap ratio of the digitally controlled oscillator (DCO) between the second and third loops, ensuring stable loop switching. The total power consumption of the WBPLL varies with the frequency range, consuming between 8.8 mW at the WBPLL minimum output frequency of 1.9 GHz and 12.8 mW at the WBPLL maximum output frequency of 6.1 GHz, all at a 1.0 V supply. Implemented in a 28 nm CMOS process, the WBPLL occupies an area of 0.055 mm2.

Investigation of low-GWP working fluids as substitutes for R245fa in organic Rankine cycle application

This study presents a thermo-economic assessment of three low-global-warming-potential (GWP) substitutes, R1233zd(E), R1234ze(Z) and R1234ze(E), for R245fa used in organic Rankine cycle (ORC) systems, considering two models with different heat sources. The exhaust heat from a diesel generator is served as heat source of Model I, while the waste heat of exhaust and jacket cooling water are used as heat source of Model II. It is noted that the working pressure of R1234ze(E) is much higher than that of R1233zd(E), R1234ze(Z) and R245fa in a fixed evaporation-temperature range. Furthermore, the system using R1234ze(E) has the minimum net power output for Model I, while it turns into the maximum net power output for Model II. In addition, both R1234ze(Z) and R1233zd(E) can be used as good alternative working fluids for R245fa because R1234ze(Z), R1233zd(E) and R245fa have close working pressures, maximum net power outputs, and minimum levelized energy costs. Compared to Model I, LECmin of R1233ed(E) and R1234ze(Z) are reduced by 10.8 % and 9.9 % and PBmin of R1233ed(E) and R1234ze(Z) are reduced by 11.5 % and 10.1 %, respectively, in Model II. However, R1233zd(E) has the highest minimum payback period for both Model I and Model II among the four working fluids investigated.

Heat–power decoupling for the CHP unit by utilizing heat storage in the district heating system integrated with heat pumps: Dynamic modeling and performance analysis

Heat–power decoupling is a key issue to be addressed for the combined heat and power (CHP) unit to enhance its operational flexibility, and utilizing heat storage in district heating systems represents a viable approach. The widespread adoption of heat pumps to boost heating network also increases the complexity of managing heat storage, and the quantitative impact of heat storage has significant implications during operation. To this end, dynamic models of heating networks and heat pumps were developed. A metric, the maximum maintenance time, was established to quantitatively assess heat storage utilization. Dynamic simulations and performance analyses were conducted on a 330 MW CHP unit. The results indicate that by employing heat storage, the feasible maximum and minimum output power of the heating system can be increased by 20 MW and decreased by 45.5 MW, respectively. With the integration of a heat pump, these values can further increase by 9 MW and decrease by 158 MW, respectively, significantly enhancing the operational flexibility of CHP unit.

Analytical Calculation of the No-Load Magnetic Field of a Hybrid Excitation Generator

Hybrid excitation generators combine the advantages of electric excitation motors and permanent magnet generators. Focusing on a permanent magnet generator as the object of study, an auxiliary excitation winding is introduced for voltage regulation. The main magnetic field is established by the permanent magnet, and the auxiliary excitation winding provides the magnetic potential required to regulate the air-gap magnetic field. While improving the voltage regulation performance of permanent magnet generators, it also reduces the loss of excitation windings in electrically excited generators. Based on a hybrid excitation generator with dual excitation windings, in the following article, we present a hybrid excitation generator equivalent to a full permanent magnet motor with the minimum output voltage, and an accurate subdomain model of the full permanent magnet motor is established considering the influence of slot opening. By establishing a matrix, the distribution curve of air-gap magnetic density was solved and ultimately verified using finite element analysis. The results of the present study lay a solid foundation for solving the air-gap magnetic density distribution of various parts of the hybrid excitation generator and studying its performance in the future.

Design of high gain MMIC amplifier for LEO satellite communication systems

In this paper, we present a novel design of S-band monolithic microwave integrated circuit (MMIC) amplifier based on GaAs Mesfet HFET-1102 transistor used in radiofrequency (RF) and microwave communications system. Basing on Chebyshev gain response an analytical method is used to design two stages lumped microwave amplifier. The matching networks constituted by lumped elements are transformed to T inductive networks and the resulting amplifier is optimized using RF simulator software. Thelumped optimized amplifier is then transformed to distributed amplifier and implemented on Rogers TMM3 substrate, largely used in microwave circuits. The proposed MMIC distributed amplifier is stable in the frequency band (2–4 GHz) and excellent performances are obtained in terms of very high gain reaching a peak of 34.23 dB, minimum input return loss (S11) of −8.85 dB at f=2.62 GHz, minimum output return loss (S22) of −12.21 dB at f=2.05 GHz and very good output/input isolation (S12) lower than −51.99 dB. For its excellent performances, the proposed MMIC distributed amplifier, is very suitable for use in space telecommunications as in Low Earth Orbit (LEO) satellites onboard receivers where the high gain amplifier is very important to assure the success of the space missions.

Analysis of the effect of mutual inductance on reducing output current ripple of the modified DC-DC Cuk converter

DC-DC converters exhibiting minimal input and output ripple are extensively employed across a diverse range of applications. This paper presents a proposed modification to the DC-DC Cuk converter. The converter is developed by modifying a conventional Cuk DC-DC converter to exhibit boost characteristics. The DC-DC converters possess the capability to function as versatile units that can be employed in a multitude of applications, ranging from DC-DC conversion to DC-AC conversion (inversion). This paper presents a novel DC-DC converter design that aims to achieve reduced ripple in both input and output currents. By employing the principle of mutual inductance, it is possible to further mitigate the presence of ripple current. The analysis of the impact of mutual inductance on the output voltage and ripple current of the proposed converter has been conducted. The validity of the derived analytical method has been confirmed through both simulated and experimental investigations. The utilization of mutual inductance in the proposed modified Cuk converter has been demonstrated to result in reduced current ripple.

Low-power DC-DC converters for smart and environmentally-friendly electric vehicles: design, simulation, and fabrication on a glass substrate

This research focuses on evaluating and comparing different DC-DC converter designs, specifically for low power applications. The study considers inductor-based, switching capacitor, and linear voltage regulator (LVR) DC-DC converters. While there has been critical investigation of DC-DC converters in the literature, there is a gap in assessing their performance based on a comprehensive set of conflicting parameters. Additionally, there is a lack of research on matching the most suitable DC-DC converter with specific low power applications. The chosen application for this study is a DC-DC converter on a glass substrate, specifically for smart glass in electric vehicles. The research presents a complete process that includes design, simulation, layout, fabrication, and measurement. Through simulations, a 4.8 V to 3.3 V buck converter is recommended, demonstrating an almost ideal response time and minimal output ripples. Experimental measurements also confirm a low output ripple of 0.3 %. By addressing this research gap and providing a comprehensive evaluation of DC-DC converters, this study contributes to the development of efficient and reliable power solutions for smart glass applications in electric vehicles.

Hemodynamics of ventricular-arterial coupling under enhanced external counterpulsation: An optimized dual-source lumped parameter model

Background and objectiveEnhanced external counterpulsation (EECP) is a mechanically assisted circulation technique widely used in the rehabilitation and management of ischemic cardiovascular diseases. It contributes to cardiovascular functions by regulating the afterload of ventricle to improve hemodynamic effects, including increased diastolic blood pressure at aortic root, increased cardiac output and enhanced blood perfusion to multiple organs including coronary circulation. However, the effects of EECP on the coupling of the ventricle and the arterial system, termed ventricular-arterial coupling (VAC), remain elusive. We aimed to investigate the acute effect of EECP on the dynamic interaction between the left ventricle and its afterload of the arterial system from the perspective of ventricular output work. MethodsA neural network assisted optimization algorithm was proposed to identify the ordinary differential equation (ODE) relation between aortic root blood pressure and flow rate. Based on the optimized order of ODE, a lumped parameter model (LPM) under EECP was developed taking into consideration of the simultaneous action of cardiac and EECP pressure sources. The ventricular output work, in terms of aortic pressure and flow rate cooperated with the LPM, was used to characterize the VAC of ventricle and its afterload. The VAC subjected to the principle of minimal ventricular output work was validated by solving the Euler-Poisson equation of cost function, ultimately determining the waveforms of aortic pressure and flow rate. ResultsA third-order ODE can precisely describe the hemodynamic relationship between aortic pressure and flow rate. An optimized dual-source LPM with three energy-storage elements has been constructed, showing the potential in probing VAC under EECP. The LPM simulation results demonstrated that the VAC in terms of aortic pressure and flow rate yielded to the minimal ventricular output work under different EECP pressures. ConclusionsThe ventricular-arterial coupling under EECP is subjected to the minimal ventricular output work, which can serve as a criterion for determining aortic pressure and flow rate. This study provides insight for the understanding of VAC and has the potential in characterizing the performance of the ventricular and arterial system under EECP.

A comprehensive comparison of the two MPPT techniques (P&amp;O, SMC) for photovoltaic systems

This paper aims to study the behavior of different maximum power point tracking (MPPT) techniques applied to PV systems. In this work, we evaluate and compare perturbation and observation (P&amp;O) and sliding mode control (SMC) techniques. a DC/DC boost converter is used between the PV system and load to transfer the maximum possible power. the conventional MPPT methods Perturb and Observe (P&amp;O) cannot detect and track the highest peak. Thus, this causes an important loss of power, so a technique is suggested sliding mode control, which offers many benefits such as durability against parameter changes, minimal current output distortion, and excellent reference tracking. The simulation results shown in MATLAB confirm that the sliding mode control method allows to have a faster response compared to P&amp;O, to reduce the steady-state fluctuations and better track the maximum power point with fewer power losses.