Low Space Utilization Research Articles

Design of CTP liquid cooling battery pack and thermal Characterization experiments

Range has emerged as a significant barrier to the advancement of electric vehicles, necessitating the development of high-energy–density battery packs. However, the conventional battery integration method, CTM (Cell to Module), has a relatively low space utilization rate, which presents a challenge to the enhancement of vehicle range. Consequently, a novel battery pack integration method, CTP (Cell to Pack), has emerged as a potential solution. In order to enhance the integration degree and effective energy density of the battery pack, a CTP and a symmetric serpentine runner liquid cooling plate are proposed in this paper. A thermal model of a single cell was constructed, and the cooling performance of the battery pack under different discharge conditions was analyzed. The optimal inlet water temperature and coolant mass flow rate were then determined. The findings indicate that the battery pack devised in this study exhibits commendable cooling capabilities and is capable of satisfying the cooling requirements associated with a 2C discharge scenario. Furthermore, when the battery pack is operated under Chinese Light Vehicle Driving Conditions (CLTC), the inlet flow rate of 2 L/min has been observed to reduce the maximum temperature differential by 1.31 °C in comparison to a scenario without internal coolant circulation.

Design and Optimization of One Special Microperforated Plate-Labyrinth Coupled Structure (MPPS-LS): From the View of Numerical Simulation

Controlling large-wavelength acoustic waves via small-size structures is an important direction for the field of noise control. Since porous acoustic material can only absorb low-frequency sound waves when their thickness is approximately one-fourth of the wavelength, such acoustic material is not effective when controlling the large-wavelength acoustic waves with small-size structures. Therefore, the resonant acoustic material has been usually chosen to absorb low-frequency sound waves instead. As a typical resonant acoustic material, microperforated plate structures (MPPS), need one large cavity with low space utilization to absorb the low-frequency acoustic waves. The microperforated plate-labyrinth coupled structure (MPPS-LS) has been proposed with the goal of improving low-frequency sound absorption ability, which is consisted of a MPPS and three separated second-order LS coupled together. The mathematical model has been established using the acousto-electric analogy method and transfer matrix method to examine the impact of the structural parameters of each part on the acoustic characteristics. According to this study, the coupled structure is compact in size and has a good low and medium-frequency acoustic absorption effect, combining low and medium-frequency acoustic absorption characteristics of both the MPPS and LS. The sound absorption of the structure after optimized design is testing using impedance tube.

Phenolic resin filled wood-derived hierarchically porous carbon monolith for high areal capacitance supercapacitors

Wood-based electrodes are widely used in supercapacitors due to their renewable and three-dimensional self-supported properties. Low space utilization of wood-based electrodes seriously restricts its practical applications. In this paper, a wood/phenolic resin composite was designed, which can effectively enhance the space utilization of wood and ensure a hierarchical porous structure. The prepared balsa wood/phenolic resin composite-derived electrode obtained a high areal capacitance (8169 mF cm–2), which is 954 % of pure balsa wood-based electrode. Moreover, the assembled symmetrical supercapacitor device exhibits outstanding electrochemical performance, displaying a high areal capacitance of 3.3 F cm–2, and a competitive volumetric energy density of 2.88 mWh cm–3. More importantly, this design has been successfully used to prepare various species wood-derived electrodes. Therefore, as a general strategy, which gives a novel idea for the design of wood-derived electrodes and may affect other fields using wood-based materials.

An indoor delivery robot based on YOLOv8 and ROS

Abstract Aiming at the problems of inflexible movement, poor operation efficiency, low space utilization in the storage area and poor compatibility of placed items, intelligent route planning ability and weak intelligent obstacle avoidance ability in the current indoor delivery robot operation process, this paper takes ROS combined with YOLOv8 as the intelligent driving core, uses the A* algorithm to make the robot go to the target position, plan a reasonable route, take STM32 as the intelligent control core, and use the Mecanum wheel as the power take-off wheel. Based on this, an indoor delivery robot based on ROS and the McNum wheel motion scheme is designed. This paper designs the robot as a whole, designs the mechanical structure and functional modules of the robot, and simulates and analyzes the obstacle avoidance scheme and key functions of intelligent driving. Experiments have proved that the design of the delivery robot can not only achieve efficient and accurate distribution, but also reduce energy consumption to a certain extent, and provide new ideas for the intelligent transformation and development of the logistics industry.

Numerical investigation on thermal-hydraulic performance of variable cross section printed circuit heat exchanger

CO2 transcritical power cycle (CTPC) systems have attracted considerable research focus in the fields of thermoelectric conversion and waste heat recovery. The regenerator is a key component affecting the CTPC system's efficiency. To improve the comprehensive performance of the regenerator, extensive research has been conducted to optimize the regenerator flow channel design. However, the optimization of the traditional Z-channel printed circuit heat exchanger structure (ZPCHE) is limited to constant cross-sectional configurations along the flow direction, which can lead to low channel space utilization. To solve this problem, an efficient variable cross section Z-channel structure (UAPCHE) is proposed in this study. The structure is designed with different cross-sectional shapes along the flow direction to fit the flow path of the main fluid. UAPCHE achieves a coordinated optimization of the heat transfer (Nu), flow (dP), and compactness performance (Q/V) by increasing the effective utilization of the channel space and weakening the damage to the fluid boundary layer. The design principle of the UAPCHE is introduced, and based on this, the structural parameters of the UAPCHE are optimized to achieve the best comprehensive performance. The results show that, compared with the ZPCHE, Nu of UAPCHE can be increased by 16.79%, dP can be reduced by 19.48%, and Q/V can be increased by 22.65%.

Design and damping performance analysis of a multistage meandering hybrid valved magnetorheological damper

Abstract The current valved magnetorheological damper has a low space utilization of the piston head, which results in insufficient output damping force, and this paper proposed a multistage meandering hybrid valved magnetorheological damper. The three-dimensional structure of the damper is established and its mathematical model is derived. The electromagnetic field finite element analysis was used to simulate the damper structure, and a comparison was made between the results of traditional annular valve structures and those of multistage meandering hybrid valve. The damping performance of a multistage meandering hybrid valved damper was experimentally studied. The results indicate that the maximum output damping force of the multistage meandering hybrid valved structure is increased by 62.2% over the traditional annular valved structure at a current of 2.4 A and a coil turn count of 350 turns. The structure can effectively utilize the piston head space and improve the output damping force of the damper. The output damping force of the damper reaches 486.4N and the adjustable coefficient K reaches 8.6. The numerical simulation results are the same as the actual experimental results.

Microscopic experiment on efficient construction of underground gas storages converted from water-invaded gas reservoirs

Based on the microfluidic technology, a microscopic visualization model was used to simulate the gas injection process in the initial construction stage and the bottom water invasion/gas injection process in the cyclical injection-production stage of the underground gas storage (UGS) rebuilt from water-invaded gas reservoirs. Through analysis of the gas-liquid contact stabilization mechanism, flow and occurrence, the optimal control method for lifecycle efficient operation of UGS was explored. The results show that in the initial construction stage of UGS, the action of gravity should be fully utilized by regulating the gas injection rate, so as to ensure the macroscopically stable migration of the gas-liquid contact, and greatly improve the gas sweeping capacity, providing a large pore space for gas storage in the subsequent cyclical injection-production stage. In the cyclical injection-production stage of UGS, a constant gas storage and production rate leads to a low pore space utilization. Gradually increasing the gas storage and production rate, that is, transitioning from small volume to large volume, can continuously break the hydraulic equilibrium of the remaining fluid in the porous media, which then expands the pore space and flow channels. This is conducive to the expansion of UGS capacity and efficiency for purpose of peak shaving and supply guarantee.

Design and control of a fast steering mirror based on flexible supports and piezoelectric ceramic actuators.

The use of the fast steering mirror in an optical path requires strict volume control, and traditional structures have low space-utilization efficiency, resulting in traditional actuators having limited output in narrow spaces. The design in this paper adopts a combination of flexible universal supports and piezoelectric ceramic actuators, greatly reducing the layout space of the rotating-shaft system. We accurately model the design structure and develop closed-loop control methods to further improve the closed-loop control accuracy of the system. The experimental results indicate that the developed control method effectively improves the response speed and bandwidth and thus has good potential for use in engineering applications.

Object Fingerprint Cache for Heterogeneous Memory System

Heterogeneous memory systems promise to provide both large storage capacity and high performance. Prior DRAM cache systems have metadata scalability issue and suffer from low cache hit rate, low DRAM space utilization, and significant data migration overhead. We observe that instances of an object type exhibit stable and predictable memory access patterns in its constituent cachelines and these patterns are referred to as object fingerprints. We propose the hardware-assisted cache that manages DRAM at the object type level and fetches data block at the granularity of a cacheline, by exploiting object fingerprint. To address its design challenges, we first present a software-hardware co-design to convey the software information to hardware. Second, we design multiple granularity sector caches that can be dynamically adjusted to adapt to changing behaviors and improve DRAM cache utilization. To address the challenges of large metadata storage overhead, we propose to bound possible sizes for each sector cache. Experimental results show our designs improve DRAM cache hit rate by 21.6%, boost IPC by 19.8%, and reduce data migration traffic by 51.6% on average, compared with state-of-art DRAM caches. More importantly, our online object fingerprint learning method is 2.3% inferior to the offline one in terms of IPC.

The feasibility of enhanced pore space utilization in CO2 storage reservoirs using an artificially emplaced Si-gel flow barrier

Carbon capture and storage is a key technology to abate CO2 emissions. One of the challenges towards ensuring the efficiency and the security of CO2 storage in reservoirs, such as open saline aquifers, is the low pore space utilization. This study investigates the feasibility of using an artificial Si-gel barrier to enhance pore space utilisation in such reservoirs under variable geological conditions. Conceptually, enhanced CO2 capillary trapping is achieved by emplacing a disk-shaped, low-permeability barrier above the CO2 injection point forcing the injected CO2 to migrate laterally underneath the barrier before transitioning to buoyancy-controlled migration. Multiphase fluid flow simulations were conducted to test the feasibility of this concept. Sensitivity analysis revealed that the barrier exhibits a strong control on CO2 plume geometry. Specifically, the relative impact of the barrier diameter on increasing the CO2 plume width, reducing the plume height and enhancing trapping varied between 67 and 86%. Capillary trapping was enhanced by 40–60% with a 20 m increase in barrier diameter in low permeability reservoirs. Additionally, the results indicate that the barrier can enhance the security of trapping CO2 in high permeability reservoirs. Results were tested for the South-West Hub reservoir, a case study area in Western Australia.

Development of a stator-rotor integrated piezoelectric actuator for precise joint rotation of the robotic arm

Piezoelectric rotary actuators are widely used for their high precision and large torque in various fields, such as optical engineering and aerospace. However, traditional piezoelectric rotary motors have a complex structure, requiring separate stator and rotor fixing devices, and they have a low space utilization rate, making them unsuitable for driving joint rotation of robotic arms. To address these issues, a novel stator-rotor integrated piezoelectric actuator is proposed in this paper, which uses the piezoelectric vibrator as both the driving vibration source and the rotor, simplifying the overall structure of the rotary actuator. By using in-plane longitudinal and out-of-plane bending vibration, the actuator achieves high-precision rotation along the diameter of a circular ring, while also providing a hollow structure for optical fibers and wires. Through parametric scanning finite element analysis, the size parameters of the annular rotor are determined. The contact conditions of stator and rotor is analyzed, and an intermittent contact model between stator and rotor is established. The experimental results show that the prototype motor weighs 52 g, has a rotation speed of 1470 deg/s, can bear a load of 63 mN m, and has a minimum resolution of 72 μrad. This research demonstrates the great potential of this rotating actuator for use in space optical instruments and aerospace applications.

A novel thermal desalting process using a binary string-of-beads flow array

The large mass transfer spacing in conventional solar stills causes a large mass transfer resistance and low space utilization. Convection mass transfer in vertical diffusion stills is always inhibited at small spacing due to the commonly used planar wicks. This paper presents a binary string-of-beads flow array for solar desalination using fibers instead of planar wicks, thus solving those problems and enabling coupled diffusion-convection mass transfer at small spacing. A prototype of our novel distiller with 16 mm mass transfer spacing and its experimental system are set up. Salt contamination, likely caused by splashing, is found to be tolerable at feedwater flows less than 50 L/h. At a saline water inlet temperature of 80 °C, the maximum thermal-water conversion efficiency reaches 0.81, and the maximum water productivity per unit volume reaches 56.3 kg/h/m3. Higher energy and space utilization than conventional stills and single effect vertical diffusion stills is demonstrated. A calculation model for heat and mass transfer between cold and hot water column pairs is developed for the first time, and the deviation between the calculated and experimental water productivity is less than ± 20%. This research may provide new ideas for efficient freshwater production in remote off-grid areas.

Design and Performance Analysis of Low Latency Routing Algorithm based NoC for MPSoC

The Network on Chip is appropriate where System-on-Chip technology is scalable and adaptable. The Network on Chip is a new communication architecture with a number of benefits, including scalability, flexibility, and reusability, for applications built on Multiprocessor System on a Chip (MPSoC). However, the design of efficient NoC fabric with high performance is critically complex because of its architectural parameters. Identifying a suitable scheduling algorithm to resolve arbitration among ports to obtain high-speed data transfer in the router is one of the most significant phases while designing a Network on chip based Multiprocessor System on a Chip. Low latency, throughput, space utilization, energy consumption, and reliability for Network on chip fabric are all determined by the router. The performance of the NoC system is hampered by the deadlock issues that plague conventional routing algorithms. This work develops a novel routing algorithm to address the deadlock problem. In this paper, a deterministic shortest path deadlock-free routing method is developed based on the analysis of the Turn Model. In the 2D-mesh structure, the algorithm uses separate routing methods for the odd and even columns. This minimizes the number of paths for a single channel, congestion, and latency. Two test scenarios—one with and one without a load test—were used to evaluate the proposed model. For a zero-load network, three clock cycles are utilized to transfer the packets. For the load network, five clocks are utilized to transfer the packets. The latency is measured for both cases without load and with load test and the corresponding latency is 3ns and 7ns respectively.The proposed method has an 18.57Mbps throughput. The area and power utilization for the proposed method are 69% (IO utilization) and 0.128W respectively. In order to validate the proposed method, the latency is compared with existing work and 50% latency is reduced both with and without congestion load.

A Case for Space Compaction of B-Tree Nodes on Flash Storage

It is well known that the in-use space in B-tree nodes is only two-thirds, on average. Such low space utilization is detrimental to flash storage in terms of cost as well as performance. In particular, as the database grows, the logical space waste in B-tree nodes will exacerbate the physical write amplification inside flash devices, worsening the write performance and eventually degrading transaction throughput. To address this problem, we propose two space compaction techniques for B-tree nodes: space reservation and data redistribution. The space reservation technique dynamically reserves the free space per index to prevent node split caused by future updates. Meanwhile, data redistribution redistributes records to a neighboring node before the split occurs. Experimental results using MySQL show that our approach can reduce the in-use database space by up to 40%, doubling the throughput. In addition, our approach outperforms MyRocks with less space. Our experimental results confirm that space compaction techniques obsolete on hard disks are very rewarding on flash storage.

EPSDNet: Efficient Campus Parking Space Detection via Convolutional Neural Networks and Vehicle Image Recognition for Intelligent Human-Computer Interactions.

The parking problem, which is caused by a low parking space utilization ratio, has always plagued drivers. In this work, we proposed an intelligent detection method based on deep learning technology. First, we constructed a TensorFlow deep learning platform for detecting vehicles. Second, the optimal time interval for extracting video stream images was determined in accordance with the judgment time for finding a parking space and the length of time taken by a vehicle from arrival to departure. Finally, the parking space order and number were obtained in accordance with the data layering method and the TimSort algorithm, and parking space vacancy was judged via the indirect Monte Carlo method. To improve the detection accuracy between vehicles and parking spaces, the distance between the vehicles in the training dataset was greater than that of the vehicles observed during detection. A case study verified the reliability of the parking space order and number and the judgment of parking space vacancies.

Optimization Method of Spatial Layout of Marine Industry Based on Cloud Computing

With the continuous expansion of the marine economy, a large number of problems have been encountered in the spatial layout of the marine industry, such as space intensification, low space utilization, unreasonable industrial structure, poor management system, inadequate scientific research and innovation capabilities, poor ecological environment, poor load balance, and large resource consumption, etc. In response to these problems, this study proposes to reoptimize the spatial layout of the marine industry on the basis of cloud computing. On the basis of collecting the Hilbert values of all data, all nodes are arranged in the order of construction time to improve the Hilbert R-tree structure. Then the idea of clustering is introduced to avoid data overlap. Using the spatial correlation coefficient, the access control model of the marine industry spatial layout platform is established to optimize the marine industry spatial layout under the background of cloud computing. When using the method proposed in this study, the time consumption was about 4 seconds when the number of blocks increased to 5000. Compared with 11 seconds and 7 seconds when using the other two methods, the proposed method greatly reduces the time consumed by the number of pieces of ocean remote sensing images in different query ranges under the ocean information cloud platform. The proposed method also shows good performance in the encryption and decryption test process of the pairing method. In summary, the feasibility and effectiveness of the proposed method in the optimization of the marine industry spatial layout is confirmed, which provides a suitable theoretical basis for the optimization of the marine industry spatial layout.

Anaconda-shaped spiral multi-layered triboelectric nanogenerators with ultra-high space efficiency for wave energy harvesting

<h2>Summary</h2> Shifting from fossil fuels to clean energy is urgently needed to reduce anthropogenic carbon emissions. The ocean is recognized as an important source of renewable energy (i.e., wave and tidal), yet remains underutilized due to several technical barriers such as low energy conversion efficiency. The triboelectric nanogenerator (TENG), which can efficiently convert wave energy into electricity, has emerged as a potential solution. However, the low output performance and space utilization of existing TENGs impede commercial applicability. Here, we design an anaconda-shaped spiral multi-layered triboelectric nanogenerator (ASM-TENG) to overcome those two shortcomings. Benefiting from the tandem structure, compared with conventional TENGs, the ASM-TENG can enhance total power output by 2- to 30-fold with a peak power density at 347 W m⁻³, it can also enlarge the space utilization by 2- to 8-fold up to 93.75%. Our ASM-TENG provides a new strategy to improve the overall performance of TENG, strengthening its commercial applicability and further facilitating the development of ocean renewable energy.

Carbonization‐free wood electrode with MXene‐reconstructed porous structure for all‐wood eco‐supercapacitors

AbstractTo bypass the conventional high temperature carbonization, MXene with an ultra‐high electrical conductivity and good electrochemical activity is coated on natural wood to make it a free‐standing electrode (TW). TW achieves a high electrical conductivity of 106.4 S m−1 and large capacitance of ~700 mF cm−2 at 0.5 mA cm−2. Furthermore, to overcome the low space utilization of the oversized vessels in wood which leads to a low energy density, a reconstructing strategy is used on TW to fully use the natural porous structure of wood by filling MXene aerogels in vessels. Compared with TW, the MXene aerogel‐loaded TW shows higher electrical conductivity of 323.6 S m−1 and capacitance of 930 mF cm−2 with remarkably high rate capability of 88.2% (0.5–10 mA cm−2). Additionally, an all‐wood eco‐supercapacitor is fabricated, and achieves a high energy density of 23 μW h cm−2 at 577 μW cm−2.image

Adaptive coding for DNA storage with high storage density and low coverage

The rapid development of information technology has generated substantial data, which urgently requires new storage media and storage methods. DNA, as a storage medium with high density, high durability, and ultra-long storage time characteristics, is promising as a potential solution. However, DNA storage is still in its infancy and suffers from low space utilization of DNA strands, high read coverage, and poor coding coupling. Therefore, in this work, an adaptive coding DNA storage system is proposed to use different coding schemes for different coding region locations, and the method of adaptively generating coding constraint thresholds is used to optimize at the system level to ensure the efficient operation of each link. Images, videos, and PDF files of size 698 KB were stored in DNA using adaptive coding algorithms. The data were sequenced and losslessly decoded into raw data. Compared with previous work, the DNA storage system implemented by adaptive coding proposed in this paper has high storage density and low read coverage, which promotes the development of carbon-based storage systems.

Flexible Planar Monopole Built-in GIS PD Sensor Based on Meandering Technology.

To address the problem of low space utilization of existing rigid Ultra-High Frequency (UHF) sensors for partial discharge (PD) in Gas-Insulated Switchgears (GIS) and the problem of disrupting the electric field distribution inside the GIS. This paper draws on the idea of flexible wearable antennas and introduces planar monopole antennas commonly used in the communication field as GIS PD detection sensors and carried out research on flexible planar monopole sensing technology built into GIS PD. The VSWR of monopole antenna in the UHF low band is optimized by the meandering technique. The size of the designed flexible antenna is 142 mm × 195 mm × 0.28 mm. The simulation and physical test results show that the improved monopole antenna with meandering technology has a VSWR of ≤2 in the frequency bands 570 MHz–830 MHz, 1.38 GHz–1.8 GHz, and 2.2 GHz–2.76 GHz when the bending radius is 0 mm, 200 mm, and 400 mm, respectively. The VSWR in the frequency band 450 MHz–3 GHz is ≤5. A 220 kV GIS PD detection platform was built to test the performance of the designed antenna, and the results showed that the antenna could detect the PD signal after bending deformation with a high Signal Noise Ratio (SNR).