Power Reduction Scheme Research Articles

Design of High Speed Sense Amplifiers for SRAM IC

In today's tech-driven landscape, semiconductor chips are critical to the functionality of most modern devices, requiring compact designs and low power consumption for efficient data storage and memory. SRAM (Static Random Access Memory) is key to meeting these demands. This study leverages Cadence Virtuoso software to design a high-performance sense amplifier circuit specifically tailored for low-power SRAM applications. Various power reduction strategies were explored, resulting in an optimized solution within a redesigned SRAM architecture. The study analyzes the impact of power consumption and response time of the proposed sense amplifier by adjusting key parameters, such as the transistor width-to-length (W/L) ratio, power supply, and nanoscale technology. Detailed metrics on power usage and transistor count for different configurations are presented to identify the most effective approach. Our proposed low-power sense amplifier design shows promising results, incorporating three VLSI power reduction techniques to enhance efficiency. These innovations in low-power SRAM are poised to advance memory-centric neuromorphic computing applications.

Grid Integration of Offshore Wind Energy: A Review on Fault Ride Through Techniques for MMC-HVDC Systems

Over the past few decades, wind energy has expanded to become a widespread, clean, and sustainable energy source. However, integrating offshore wind energy with the onshore AC grids presents many stability and control challenges that hinder the reliability and resilience of AC grids, particularly during faults. To address this issue, current grid codes require offshore wind farms (OWFs) to remain connected during and after faults. This requirement is challenging because, depending on the fault location and power flow direction, DC link over- or under-voltage can occur, potentially leading to the shutdown of converter stations. Therefore, this necessitates the proper understanding of key technical concepts associated with the integration of OWFs. To help fill the gap, this article performs an in-depth investigation of existing alternating current fault ride through (ACFRT) techniques of modular multilevel converter-based high-voltage direct current (MMC-HVDC) for OWFs. These techniques include the use of AC/DC choppers, flywheel energy storage devices (FESDs), power reduction strategies for OWFs, and energy optimization of the MMC. This article covers both scenarios of onshore and offshore AC faults. Given the importance of wind turbines (WTs) in transforming wind energy into mechanical energy, this article also presents an overview of four WT topologies. In addition, this article explores the advanced converter topologies employed in HVDC systems to transform three-phase AC voltages to DC voltages and vice versa at each terminal of the DC link. Finally, this article explores the key stability and control concepts, such as small signal stability and large disturbance stability, followed by future research trends in the development of converter topologies for HVDC transmission such as hybrid HVDC systems, which combine current source converters (CSCs) and voltage source converters (VSCs) and diode rectifier-based HVDC (DR-HVDC) systems.

Sustainable machining of Inconel 718 using minimum quantity lubrication: Artificial intelligence-based process modelling

Governments and industries are developing aggressive policies to reduce carbon emissions and shift from fossil fuels to renewable energy. On the other hand, industries struggle to reduce energy consumption and depend on production lot sizes to control energy requirements. In this regard, energy-efficient processing through CNC machine tools can potentially influence energy demand and requires energy-aware power consumption strategies for machining processes. For manufacturing a single product, predicting energy demand can be decisive in determining parametric control and other factors. Previously analytical models have been largely used to model machining requirements and energy demand. However, these models largely depend on parameterization and do not facilitate the integration of external sub-systems. Therefore, in this paper, an artificial intelligence-based power reduction strategy is developed and implemented on single material (Inconel 718), four control parameters (cutting speed, feed rate, depth of cut and flow rate) and two sub-systems (minimum quantity lubrication (MQL) and nanofluids-based minimum quantity lubrication (NF-MQL)). The paper employs four machine learning algorithms,’ K-Nearest Neighbor’, ‘Gaussian Regression’, ‘Decision Tree’, and ‘Logistic Regression’, to evaluate their functionality in predicting power consumption (Pc) of CNC machining systems using a real experimental data set. As per evaluation based on five performance metrics (R-square, MSE, RMSE, MAE, and MedAE), ‘Decision Tree’ has achieved the most accurate power consumption predictions. The comparative results highlight ‘Decision Tree’ as the most better predictor with the optimal max_depth of 2 showing Pc MQL R2 of 0.915 and Pc NF-MQL R2 of 0.931.

A Novel Control Scheme for Light Load Power Reduction of Flyback Converter

A Novel Control Scheme for Light Load Power Reduction of Flyback Converter

Melt pool monitoring and process optimisation of directed energy deposition via coaxial thermal imaging

In Laser-based Directed Energy Deposition of metal powder, the use of optimised parameters allows the deposition of defect-free material, while diverging from these optimised parameters can typically result in high porosity, high dilution or different track geometry. One of the main challenges when building complex geometries is that the geometrical and thermal conditions of the deposition are constantly changing, which requires to adjust the process parameters during the production. In order to facilitate this process, sensors such as thermal cameras can be used to extract data from the process and adapt the parameters to keep the process stable despite external disturbances. In this research, different signals extracted from a coaxial thermal camera are investigated and compared for process optimisation. To investigate such possibilities, five overlapped tracks are deposited at constant laser powers in order to extract average pixel values as well as the melt pool area, length, width and orientation. The behaviour of each track deposition is modelled as a function of the laser power, and these models are used to calculate and test laser power reduction strategies based on different signals. The results show that the melt pool area is the most relevant signal to use for an efficient process control, resulting in a stable process with only ±1.6 % of signal variation from track to track.

Active Power Control of DFIG Wind Turbines for Transient Stability Enhancement

This paper proposes an adaptive Dynamic Power Reduction (aDPR) scheme for Type-3 Wind Turbine-Generators (WTGs) to enhance transient stability of synchronous generators (SGs), with benefits of increasing transfer limits on already fully loaded transmission paths. The scheme consists of three components to deal with a fault close to a SG. Initially, the WTG curtails its active power to a predefined level to act as a dynamic brake for the SG. Then the controller monitors the rate of change of frequency to adaptively ramp the WTG back to its original power output while minimizing the WTG pitch and rotor motion. Finally, to reduce the risk of second-swing instability, the converter uses its reactive current to damp SG power swings. The aDPR scheme can be classified as a remedial action scheme and is enabled if its action can ensure transient stability. To demonstrate the effectiveness of aDPR and to benchmark it against other WTG active current and frequency feedback control techniques, a single-machine infinite-bus system with one WTG is utilized. Next, an aDPR enabled WTG is integrated in the NPCC 68-bus system. Finally, the aDPR controller’s ability to prevent transient instability is demonstrated on the two-area system.

Steady-state power distribution in VSC-based MTDC systems and dc grids under mixed P/V and I/V droop control

This paper proposes a steady-state power distribution derivation method for voltage source converter (VSC)-based multi-terminal HVDC (MTDC) systems and dc grids under mixed power/voltage (P/V) and current/voltage (I/V) droop control. P/V and I/V droop control are two commonly used control schemes, which can be combined to achieve co-regulation of powers & currents in MTDC systems and dc grids. The proposed method can be used to estimate the power distributions under different scenarios for MTDC systems and dc grids based on VSCs with mixed P/V and I/V droop control. After determining the initial operating point based on an estimation-correction algorithm, redistributed power due to power disturbances, current changes or converter outages is analyzed in detail considering converter overload. An excess power reduction strategy is further proposed to avoid violation of power limits after converter outage. The accuracy of the proposed method is validated through multiple scenarios in a modular multilevel converter (MMC)-based four-terminal dc grid. The comparison between the proposed method and other approaches in the current literature further demonstrates the advantages of proposed power distribution derivation method. • Determination of initial operating point for mixed P/V and I/V droop control by proposed estimation-correction algorithm. • Derivation of power redistribution after dc power/ current reference changes and converter outages. • Consideration of possible converter overloads caused by different system disturbances.

Encoding scheme for power reduction in network on chip links

Encoding scheme for power reduction in network on chip links

Enhanced Clock Gating Technique for Power Optimization in SRAM and Sequential Circuit

Low power VLSI designs are having wide variety of application usage in real-time. VLSI circuits are analyzed with various power reduction strategies. Existing approaches are used the clock frequency control, switching activity and scaling factor for power reduction. The glitching problem and clock triggering issues are higher therefore; the proposed work utilized the improved circuit of clock gating technique. In this proposed work, the enhanced clock gating with D-latch model is constructed to obtain the less power consumption. The traditional clock gating technique is improved by adding clock triggering on LATCH circuit and adding buffer circuit between the source and load circuitry to reduce the clock switching issues like gitching and clocking activity. Here the SRAM and sequential counter circuits are designed to utilize the power reduction strategy for improving the performance. This is applicable for various applications in real world and utilizing the FPGA and DSP application specific circuits. Experimental results are analyzed to obtain the power reduction result of SRAM and sequential circuit. Area, power, and delay are obtained the better results as compared with the previous work. Overall, design is performed using Xilinx 14.2 ISE suit.

Development of Strategies to Reduce Ventilation and Heating Costs in a Swedish Sublevel Caving Mine\u2014a Unique Case of LKAB\u2019s Konsuln Mine

This paper outlines a unique case of the development of strategies to reduce ventilation and heating costs in Konsuln iron ore mine in northern Sweden. The mine, located just south of Luossavaara-Kiirunavaara Aktiebolag’s Kiruna iron ore mine, was developed as a test mine 2018–2020 for the Sustainable Underground Mining (SUM) project. Besides functioning as a test mine, Konsuln also contributes ore production. The existing mine ventilation system was designed for the current production rate of 0.8 million tons per annum (Mtpa). There is a plan to increase this rate to between 1.8 and 3 Mtpa in the future, and this requires the primary fans to be upgraded. Therefore, a study was carried out to determine whether using ventilation on demand (VOD) could avoid this fan upgrade and reduce Konsuln’s ventilation and heating power costs in the future. The study also investigated whether using battery electric vehicles (BEVs) along with VOD or as a standalone strategy could further reduce these power costs. In addition, the study analyzed the suitability of heating power reduction strategies presently or previously used in the Nordic countries and Canada to investigate potential additional strategies to reduce the heating power cost, the largest portion of Konsuln’s ventilation and heating power costs. The study found using VOD can avoid the expensive upgrading of the existing primary fans and reduce Konsuln’s ventilation and heating power costs in the future. Using BEVs can further reduce these costs. Finally, none of the Nordic and Canadian heating power reduction strategies is suitable for Konsuln because they require unique conditions that do not exist in Konsuln.

Energy flexibility curves to characterize the residential space cooling sector: The role of cooling technology and emission system

Space cooling of buildings shows an increasing trend in energy use worldwide. The exploitation of the energy flexibility reserve obtainable from buildings cooling-loads management can have an important role to improve the security and the reliability of the electricity power grid. Many studies in literature assess the energy flexibility potential of air conditioning systems; however, the role of the specific cooling technology is always scarcely explored. The objective of this work is to provide an evaluation of the operational energy flexibility that can be obtained involving the most common residential space cooling technologies, paying particular attention to the distribution system (e.g., all-air system, fan-coil units with and without the addition of a thermal energy storage and hydronic massive systems). The analysis is carried out with dynamic simulation models for the various cooling systems involved. Results show a great influence of the adopted distribution system in the implementation of a flexibility request. In particular, all-air systems (i.e. split systems) show the lower flexible behavior (they require up to 10 h of precooling to be off during a peak hour). Whereas the adoption of fan coil units coupled with a thermal energy storage allows to implement different peak shaving strategies without compromising the indoor air temperature with low drawback effects in terms of anticipated electricity overconsumptions (no precooling of the air is required and a maximum of 23 % increase in electricity consumed in the time before the event occurs, with a reduction of 16 % in subsequent hours). In case of ceiling cooling systems, results highlight that as the thermal inertia of the system increases, the indoor conditions are less affected, but the anticipated overconsumption of the heat pump increases (for the same Demand Response event the electricity overconsumption goes from + 67 % to +116 %, passing from ceiling panels to concrete ceiling). The results obtained from this analysis are then used to draw flexibility curves, which aim at providing a characterization of the flexibility of a cooling system. They can be used to predict, for typical installations, the system behavior in presence of a peak power reduction strategy in terms of pre-cooling duration, energy use variation and modification of the temperature comfort bandwidth. Such predictions are important because they can provide insights on the design and operation of space cooling systems in demand side management strategies.

Low-Process–Voltage–Temperature-Sensitivity Multi-Stage Timing Monitor for System-on-Chip Applications

High performance and complex system-on-chip (SoC) design require a throughput and stable timing monitor to reduce the impacts of uncertain timing and implement the dynamic voltage and frequency scaling (DVFS) scheme for overall power reduction. This paper presents a multi-stage timing monitor, combining three timing-monitoring stages to achieve a high timing-monitoring resolution and a wide timing-monitoring range simultaneously. Additionally, because the proposed timing monitor has high immunity to the process–voltage–temperature (PVT) variation, it provides a more stable time-monitoring results. The time-monitoring resolution and range of the proposed timing monitor are 47 ps and 2.2 µs, respectively, and the maximum measurement error is 0.06%. Therefore, the proposed multi-stage timing monitor provides not only the timing information of the specified signals to maintain the functionality and performance of the SoC, but also makes the operation of the DVFS scheme more efficient and accurate in SoC design.

A Power Reduction Scheme with Partial Sleep Control of ONU Frame Buffer in Operation

A Power Reduction Scheme with Partial Sleep Control of ONU Frame Buffer in Operation

A Novel Bandwidth Efficient PTS Scheme for Peak Power Reduction in OFDM Systems

A Novel Bandwidth Efficient PTS Scheme for Peak Power Reduction in OFDM Systems

An algorithm to optimise the energy distribution of data centre electrical infrastructures

For the overriding need of storing all the data that is produced by social networks, the increase in energy consumption by e-commerce and cloud computing demands critical attention. Parallel to this surge in the use of electricity there is a long held hope for a reduction in both financial and environmental costs. What is presented here, in order to optimise energy distribution infrastructures at the data centre, is the power-balancing algorithm (PLDA-D). In order to analyse energy flow models (EFMs), the PLDA-D bases itself on the Bellman and Ford-Fulkerson flow algorithms. Power efficiency, sustainability, and cost metrics of data centre infrastructures constitute the elements for EFM computation. The case study that follows analysed four power infrastructures to demonstrate practical applications for power reduction strategies. A 3.8% reduction in sustainability impact and operational costs is shown by the results obtained.

An algorithm to optimise the energy distribution of data centre electrical infrastructures

For the overriding need of storing all the data that is produced by social networks, the increase in energy consumption by e-commerce and cloud computing demands critical attention. Parallel to this surge in the use of electricity there is a long held hope for a reduction in both financial and environmental costs. What is presented here, in order to optimise energy distribution infrastructures at the data centre, is the power-balancing algorithm (PLDA-D). In order to analyse energy flow models (EFMs), the PLDA-D bases itself on the Bellman and Ford-Fulkerson flow algorithms. Power efficiency, sustainability, and cost metrics of data centre infrastructures constitute the elements for EFM computation. The case study that follows analysed four power infrastructures to demonstrate practical applications for power reduction strategies. A 3.8% reduction in sustainability impact and operational costs is shown by the results obtained.

Energy-Efficient Data-Aware SRAM Design Utilizing Column-Based Data Encoding

This brief presents an ultra-low power SRAM utilizing a column-based data encoding scheme for power reduction. The proposed scheme is particularly beneficial in applications like bio-signal and image processing where neighboring data have similar values. The proposed technique generates write data through bit-wise comparison, which leads to a larger number of “0s”. To utilize this, a data-aware bitline pre-charge scheme is proposed to minimize the write power for “0”. In addition, a PVT-tracking bias generator compensates for the read bitline leakage to improve the sensing margin. A 32Kb SRAM in 65nm CMOS technology shows successful operation down to 0.36 V with the power of 0.37 μW and the maximum frequency of 0.25 MHz. The minimum energy is 0.3 pJ/access at 0.5 V.

Power Reduction with Sleep/Wake on Redundant Data (SWORD) in a Wireless Sensor Network for Energy-Efficient Precision Agriculture

The use of wireless sensor networks (WSNs) in modern precision agriculture to monitor climate conditions and to provide agriculturalists with a considerable amount of useful information is currently being widely considered. However, WSNs exhibit several limitations when deployed in real-world applications. One of the challenges faced by WSNs is prolonging the life of sensor nodes. This challenge is the primary motivation for this work, in which we aim to further minimize the energy consumption of a wireless agriculture system (WAS), which includes air temperature, air humidity, and soil moisture. Two power reduction schemes are proposed to decrease the power consumption of the sensor and router nodes. First, a sleep/wake scheme based on duty cycling is presented. Second, the sleep/wake scheme is merged with redundant data about soil moisture, thereby resulting in a new algorithm called sleep/wake on redundant data (SWORD). SWORD can minimize the power consumption and data communication of the sensor node. A 12 V/5 W solar cell is embedded into the WAS to sustain its operation. Results show that the power consumption of the sensor and router nodes is minimized and power savings are improved by the sleep/wake scheme. The power consumption of the sensor and router nodes is improved by 99.48% relative to that in traditional operation when the SWORD algorithm is applied. In addition, data communication in the SWORD algorithm is minimized by 86.45% relative to that in the sleep/wake scheme. The comparison results indicate that the proposed algorithms outperform power reduction techniques proposed in other studies. The average current consumptions of the sensor nodes in the sleep/wake scheme and the SWORD algorithm are 0.731 mA and 0.1 mA, respectively.

A Low-Power Post-LPDDR4 Interface Using AC Termination at RX and an Active Inductor at TX

A power reduction scheme that uses ac termination at receiver (RX) and a transmitter (TX) output driver with an active inductor part (AIP) is proposed for a point-to-point post-low-power mobile DRAM4 interface at 8 Gb/s. AC termination at the RX I/O can reduce the power consumption by preventing dc power loss. However, this causes inter symbol interference (ISI), owing to the difference in gain depending on the frequency. Thus, ac termination generates more jitter, which results in a smaller eye-opening than the conventional on-die termination. The AIP in the TX output driver reduces the low-frequency gain and the ISI caused by the ac termination. This reduces the jitter and improves the eye-opening. The proposed AIP allows changing the frequency range by adjusting the resistance ( ${R}_{\mathrm{AI}}$ ), capacitance ( ${C} _{\mathrm{AI}}$ ), and the size of the MOSFET according to the resistance ( ${R} _{\mathrm{ac}}$ ) and capacitance ( ${C} _{\mathrm{ac}}$ ) used in the ac termination at the RX. In this brief, the ac termination at the RX and the AIP in the TX were implemented in a 28-nm CMOS process and operated at 8 Gb/s with a 3-inch FR4 microstrip line including a board and a socket model. The proposed transceiver chip achieves a peak-to-peak jitterof 43.6 ps and power reduction of 31% compared with chips without ac termination and AIP.

The micro-dynamics of power and performance in focus groups: an example from discussions on national identity with the South Sudanese diaspora in the UK

In recent years there has been an increasing recognition that both the content of focus group discussions and the interaction that takes place form indivisible facets of focus group data. Interaction, however, is not a neutral activity but one that is infused with the dynamics of power in wider society and in the immediate context of the discussion. I use Bourdieu’s notion of fields of power to analyse focus group discussions on national identity with South Sudanese diaspora in the UK. I argue that the micro-dynamics of power in focus group discussions have relevance to the relations of power in the population group from which participants are purposively sampled and, consequently, their observation enriches research findings. Further, I observe that the guidance literature on the conduct of focus group discussions encourages power-reduction strategies, and requires updating to allow space for the power-infused character of social interaction to manifest itself.