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Journal articles on the topic 'Compression'
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GROSU-BULARDA, Andreea, Razvan Nicolae TEODOREANU, Andra-Luana LAZARESCU, Marius POPESCU, Florin-Vlad HODEA, Flavia Francesca LITA, Alexandru STOIAN, Cristian VANCEA, Liviu Petre COJOCARU, and Ioan LASCAR. "Nerve compression due to benign tumors or ganglion cysts in the upper limb – case series." Romanian Journal of Medical Practice 16, no. 4 (December 31, 2021): 501–8. http://dx.doi.org/10.37897/rjmp.2021.4.19.
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Tumor nerve compressions in the upper limb are relatively rare, usually involving ganglion cysts and benign tumors. We present a case series of five patients with peripheral nerve compression in the upper limb due to tumor or cystic masses- ulnar nerve compression in the Guyon’s tunnel due to a ganglion cyst, large median nerve schwannoma compressing anterior interosseous nerve and median nerve, voluminous lipoma compressing median nerve in the proximal forearm, superficial branch of radial nerve compression by a synovial cyst and elbow region lipoma compressing radial nerve. In the beginning, those benign lesions are asymptomatic but, as they continue to grow adjacent to a peripheral nerve clinical manifestations appear progressively as compressive neuropathies. After a preoperative imagistic analysis, tumor resection with careful dissection, in order to preserve the neurovascular structures, is the elective surgical procedure in order to obtain an optimal functional recovery.
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Isechi, Kohei. "Light Field Compression for Compressive 3D Display." International Journal of Machine Learning and Computing 9, no. 2 (April 2019): 208–12. http://dx.doi.org/10.18178/ijmlc.2019.9.2.788.
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Ma, Wei Hua, and Hong Zhen Kang. "Experimental Study on Compressive Behavior of CFRP Confined Concrete Columns." Advanced Materials Research 446-449 (January 2012): 3725–29. http://dx.doi.org/10.4028/www.scientific.net/amr.446-449.3725.
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Compressive tests of 30 concrete column specimens with three concrete strength grades are carried out in this paper to study ultimate compressive strength of specimens. The specimens are divided into three groups, that is, unconfined, confined by CFRP with no initial compression and confined by CFRP with various initial compressions. The different initial compressions’ influence on ultimate stresses and strains are investigated. The decrease of CFRP reinforcing effect due to pre-compression are analyzed. The research results provide experimental datum for reinforced design of existing concrete columns.
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Ko, Yousun, Alex Chadwick, Daniel Bates, and Robert Mullins. "Lane Compression." ACM Transactions on Embedded Computing Systems 20, no. 2 (March 2021): 1–26. http://dx.doi.org/10.1145/3431815.
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This article presents Lane Compression, a lightweight lossless compression technique for machine learning that is based on a detailed study of the statistical properties of machine learning data. The proposed technique profiles machine learning data gathered ahead of run-time and partitions values bit-wise into different lanes with more distinctive statistical characteristics. Then the most appropriate compression technique is chosen for each lane out of a small number of low-cost compression techniques. Lane Compression’s compute and memory requirements are very low and yet it achieves a compression rate comparable to or better than Huffman coding. We evaluate and analyse Lane Compression on a wide range of machine learning networks for both inference and re-training. We also demonstrate the profiling prior to run-time and the ability to configure the hardware based on the profiling guarantee robust performance across different models and datasets. Hardware implementations are described and the scheme’s simplicity makes it suitable for compressing both on-chip and off-chip traffic.
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P, Srividya. "Optimization of Lossless Compression Algorithms using Multithreading." Journal of Information Technology and Sciences 9, no. 1 (March 2, 2023): 36–42. http://dx.doi.org/10.46610/joits.2022.v09i01.005.
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The process of reducing the number of bits required to characterize data is referred to as compression. The advantages of compression include a reduction in the time taken to transfer data from one point to another, and a reduction in the cost required for the storage space and network bandwidth. There are two types of compression algorithms namely lossy compression algorithm and lossless compression algorithm. Lossy algorithms find utility in compressing audio and video signals whereas lossless algorithms are used in compressing text messages. The advent of the internet and its worldwide usage has not only raised the utility but also the storage of text, audio and video files. These multimedia files demand more storage space as compared to traditional files. This has given rise to the requirement for an efficient compression algorithm. There is a considerable improvement in the computing performance of the machines due to the advent of the multi-core processor. However, this multi-core architecture is not used by compression algorithms. This paper shows the implementation of lossless compression algorithms namely the Lempel-Ziv-Markov Algorithm, BZip2 and ZLIB algorithms using the concept of multithreading. The results obtained prove that the ZLIB algorithm proves to be more efficient in terms of the time taken to compress and decompress the text. The comparison is done for both compressions without multithreading and compression with multi-threading.
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P, Srividya. "Optimization of Lossless Compression Algorithms using Multithreading." Journal of Information Technology and Sciences 9, no. 1 (March 1, 2023): 36–42. http://dx.doi.org/10.46610/joits.2023.v09i01.005.
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The process of reducing the number of bits required to characterize data is referred to as compression. The advantages of compression include a reduction in the time taken to transfer data from one point to another, and a reduction in the cost required for the storage space and network bandwidth. There are two types of compression algorithms namely lossy compression algorithm and lossless compression algorithm. Lossy algorithms find utility in compressing audio and video signals whereas lossless algorithms are used in compressing text messages. The advent of the internet and its worldwide usage has not only raised the utility but also the storage of text, audio and video files. These multimedia files demand more storage space as compared to traditional files. This has given rise to the requirement for an efficient compression algorithm. There is a considerable improvement in the computing performance of the machines due to the advent of the multi-core processor. However, this multi-core architecture is not used by compression algorithms. This paper shows the implementation of lossless compression algorithms namely the Lempel-Ziv-Markov Algorithm, BZip2 and ZLIB algorithms using the concept of multithreading. The results obtained prove that the ZLIB algorithm proves to be more efficient in terms of the time taken to compress and decompress the text. The comparison is done for both compressions without multithreading and compression with multi-threading.
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Guerra, Aníbal, Jaime Lotero, José Édinson Aedo, and Sebastián Isaza. "Tackling the Challenges of FASTQ Referential Compression." Bioinformatics and Biology Insights 13 (January 2019): 117793221882137. http://dx.doi.org/10.1177/1177932218821373.
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The exponential growth of genomic data has recently motivated the development of compression algorithms to tackle the storage capacity limitations in bioinformatics centers. Referential compressors could theoretically achieve a much higher compression than their non-referential counterparts; however, the latest tools have not been able to harness such potential yet. To reach such goal, an efficient encoding model to represent the differences between the input and the reference is needed. In this article, we introduce a novel approach for referential compression of FASTQ files. The core of our compression scheme consists of a referential compressor based on the combination of local alignments with binary encoding optimized for long reads. Here we present the algorithms and performance tests developed for our reads compression algorithm, named UdeACompress. Our compressor achieved the best results when compressing long reads and competitive compression ratios for shorter reads when compared to the best programs in the state of the art. As an added value, it also showed reasonable execution times and memory consumption, in comparison with similar tools.
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Wang, Hong Yun, and Hui Qiang Zheng. "Shear and Squeeze Rheometry of Magnetorheological Fluids." Advanced Materials Research 305 (July 2011): 344–47. http://dx.doi.org/10.4028/www.scientific.net/amr.305.344.
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The mechanical properties of a magnetorheological (MR) fluid in shearing, compression and shearing after compression have been studied in the magnetic field which is generated by a coil carrying different magnitudes of DC electrical current on a self-constructed test system. The relations of compression stress versus compression strain, yield stress versus compression stress were studied under different magnetic fields. The compressing tests showed that the MR fluid is very stiff at small compressive strains lower than 0.13. The shear yield stress of MR fluids after compression was much stronger than that of uncompressed MR fluids under the same magnetic field. The enhanced shear yield stress of MR fluids can be utilized to design the MR clutch and brake for new structure and will make MR fluids technology attractive for many applications.
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Yedukondalu, G., Sajjan Patnaik, P. Lakshmi Venkatesh, and S. Siva Jagadeesh. "Chest compression with 2-DOF parallel manipulator for cardiopulmonary resuscitation." International Journal of Engineering & Technology 7, no. 2.8 (March 19, 2018): 211. http://dx.doi.org/10.14419/ijet.v7i2.8.10411.
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Chest compression process is used for recovering patients who met with a cardiac arrest in emergency situations. Chest compression is the only possibility of rescuing patients during cardiopulmonary resuscitation (CPR). It is hard to achieve the exact chest compression’s depth and rate even by experienced professionals as per the CPR guideline. A 2-DOF 2-RRR translational parallel manipulator was designed for delivering chest compressions. The kinematic analysis is carried out analytically.The workspace of the manipulator is examined in consideration of physical constraints imposed by joints. Finally, the manipulator operates with exact compression depth and rate during CPR.
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Mishra, Amit Kumar. "Versatile Video Coding (VVC) Standard: Overview and Applications." Turkish Journal of Computer and Mathematics Education (TURCOMAT) 10, no. 2 (September 10, 2019): 975–81. http://dx.doi.org/10.17762/turcomat.v10i2.13578.
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Information security includes picture and video compression and encryption since compressed data is more secure than uncompressed imagery. Another point is that handling data of smaller sizes is simple. Therefore, efficient, secure, and simple data transport methods are created through effective data compression technology. Consequently, there are two different sorts of compression algorithm techniques: lossy compressions and lossless compressions. Any type of data format, including text, audio, video, and picture files, may leverage these technologies. In this procedure, the Least Significant Bit technique is used to encrypt each frame of the video file format to be able to increase security. The primary goals of this procedure are to safeguard the data by encrypting the frames and compressing the video file. Using PSNR to enhance process throughput would also enhance data transmission security while reducing data loss.
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Eldstål-Ahrens, Albin, Angelos Arelakis, and Ioannis Sourdis. "L 2 C: Combining Lossy and Lossless Compression on Memory and I/O." ACM Transactions on Embedded Computing Systems 21, no. 1 (January 31, 2022): 1–27. http://dx.doi.org/10.1145/3481641.
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In this article, we introduce L 2 C, a hybrid lossy/lossless compression scheme applicable both to the memory subsystem and I/O traffic of a processor chip. L 2 C employs general-purpose lossless compression and combines it with state-of-the-art lossy compression to achieve compression ratios up to 16:1 and to improve the utilization of chip’s bandwidth resources. Compressing memory traffic yields lower memory access time, improving system performance, and energy efficiency. Compressing I/O traffic offers several benefits for resource-constrained systems, including more efficient storage and networking. We evaluate L 2 C as a memory compressor in simulation with a set of approximation-tolerant applications. L 2 C improves baseline execution time by an average of 50% and total system energy consumption by 16%. Compared to the lossy and lossless current state-of-the-art memory compression approaches, L 2 C improves execution time by 9% and 26%, respectively, and reduces system energy costs by 3% and 5%, respectively. I/O compression efficacy is evaluated using a set of real-life datasets. L 2 C achieves compression ratios of up to 10.4:1 for a single dataset and on average about 4:1, while introducing no more than 0.4% error.
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HAN, FENGXIA, QING LIU, XIN GUO, MENG ZHANG, and XIA HAN. "ANALYTICAL STUDY ON AXIAL AND ECCENTRIC COMPRESSIVE BEHAVIOR OF POPLAR COLUMN STRENGTHENED BY BFRP." WOOD RESEARCH 67(1) 2022 67, no. 1 (January 16, 2022): 11–25. http://dx.doi.org/10.37763/wr.1336-4561/67.1.1125.
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In this work, the compression behaviour of the Xinjiang poplar column was reinforced by basalt fibre reinforced polymer (BFRP) strips with different reinforced configurations, and thenumerical simulations were performed on the axial and eccentric compressions of poplar columns unreinforced and reinforced with BFRP to assess the effect of the bearing capacity and deformation of the columns. The results show that the use of BFRP to reinforce the Xinjiang poplar column effectively improves its axial compressive bearing capacity (axial compression) andbending bearing capacity (eccentric compression), and at the same time, the bearing capacity and stiffness of the columns strengthened by BFRP increased with the bonding area of BFRP.
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Fortin, M., J. Soulhat, A. Shirazi-Adl, E. B. Hunziker, and M. D. Buschmann. "Unconfined Compression of Articular Cartilage: Nonlinear Behavior and Comparison With a Fibril-Reinforced Biphasic Model." Journal of Biomechanical Engineering 122, no. 2 (October 18, 1999): 189–95. http://dx.doi.org/10.1115/1.429641.
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Mechanical behavior of articular cartilage was characterized in unconfined compression to delineate regimes of linear and nonlinear behavior, to investigate the ability of a fibril-reinforced biphasic model to describe measurements, and to test the prediction of biphasic and poroelastic models that tissue dimensions alter tissue stiffness through a specific scaling law for time and frequency. Disks of full-thickness adult articular cartilage from bovine humeral heads were subjected to successive applications of small-amplitude ramp compressions cumulating to a 10 percent compression offset where a series of sinusoidal and ramp compression and ramp release displacements were superposed. We found all equilibrium behavior (up to 10 percent axial compression offset) to be linear, while most nonequilibrium behavior was nonlinear, with the exception of small-amplitude ramp compressions applied from the same compression offset. Observed nonlinear behavior included compression-offset-dependent stiffening of the transient response to ramp compression, nonlinear maintenance of compressive stress during release from a prescribed offset, and a nonlinear reduction in dynamic stiffness with increasing amplitudes of sinusoidal compression. The fibril-reinforced biphasic model was able to describe stress relaxation response to ramp compression, including the high ratio of peak to equilibrium load. However, compression offset-dependent stiffening appeared to suggest strain-dependent parameters involving strain-dependent fibril network stiffness and strain-dependent hydraulic permeability. Finally, testing of disks of different diameters and rescaling of the frequency according to the rule prescribed by current biphasic and poroelastic models (rescaling with respect to the sample’s radius squared) reasonably confirmed the validity of that scaling rule. The overall results of this study support several aspects of current theoretical models of articular cartilage mechanical behavior, motivate further experimental characterization, and suggest the inclusion of specific nonlinear behaviors to models. [S0148-0731(00)00702-0]
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Lee, Jae-Min, and Hyeong-Wan Yun. "Effect of Chest Compression Position Depending on the Rescuer’s Hip Joint Angle During Basic CPR." Fire Science and Engineering 34, no. 2 (April 30, 2020): 103–9. http://dx.doi.org/10.7731/kifse.0902eaff.
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This study aims to investigate the improvement in basic CPR quality on the basis of the hip joint angle of the rescuer among students in the Department of Emergency Medical Technology who completed a basic CPR curriculum. In this study, we carried out a comparative analysis using SimPad SkillReporter and Resusci Anne® QCPR® to measure the quality of CPR (depth of chest compressions, full relaxation, compression speed, and more) on the basis of the rescuer’s hip joint angle in accordance with the 2015 AHA Guidelines and conducted chest compressions and CPR 5 times in a 30:2 ratio. It was found that maintenance of the rescuer’s hip joint angle at 90 degrees while compressing and relaxing the chest made a statistically significant difference in both the experimental and control groups. Moreover, this indicated that the closer the hip joint angle was to 90 degrees, the better was the quality of basic CPR. However, there was no significant difference in the hip joint angle, degree of CPR, depth of chest compressions, chest compression speed, chest compression and relaxation percentages (%), accuracy of chest compressions, hands-off time during CPR, and percentage of chest compression time (p > 0.05). Maintaining the hip joint angle at 90 degrees for basic CPR was not significantly different from not maintaining this angle. Nonetheless, good results have been obtained at moderate depth and 100% recoil. Therefore, good outcome and high-quality CPR are expected.
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George, Bernard, and Claude Laurian. "Impairment of Vertebral Artery Flow Caused by Extrinsic Lesions." Neurosurgery 24, no. 2 (February 1, 1989): 206–14. http://dx.doi.org/10.1227/00006123-198902000-00009.
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Abstract In a consecutive series of 71 cases of extrinsic lesions involving the vertebral artery (VA), 51 patients presented with external compression of this vessel. The compressive agents included 34 tumors, 4 osteophytes, 5 fibrous bands, 4 traumatic lesions, 2 neural elements, and 2 infectious processes. The main site was the second portion of the VA (C2-C6) (30 of 51 patients). Compression always induced at least significant stenosis, and in 8 patients caused complete occlusion. The compression was either permanent (44 patients) or intermittent (7 patients). Symptoms were observed in 11 patients, including 2 with permanent deficits. Surgical release of compression was performed each time symptoms could be explained by a reduction in VA flow and also when the compressing agent needed to be removed, as in the cases involving tumors. VA decompression was achieved by direct approach in 37 patients, by reduction and fixation of a traumatic dislocation in 2 patients, and by distal revascularization in 4 patients. Medical treatment or roentgenotherapy was used in the other patients. Results were excellent in all but 2 patients, who died from traumatic and ischemic lesions, respectively. Therefore, it seems important to identify external causes of compression of the VA for two reasons: 1) to suppress symptoms of vertebrobasilar insufficiency when their relation to VA compression is clearly established, and 2) to remove compressive agents like turnors safely while preserving the VA.
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Sarinova, Assiya, Alexandr Neftissov, Leyla Rzayeva, Alimzhan Yessenov, Lalita Kirichenko, and Ilyas Kazambayev. "Development of an algorithm for compressing aerospace images for the subsequent recognition and identification of various objects." Information technology. Industry control systems 3, no. 2 (129) (June 28, 2024): 83–94. http://dx.doi.org/10.15587/1729-4061.2024.306973.
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The object of study is the recognition and identification of various objects in aerospace images. To solve the problems of compressing hyperspectral aerospace images with losses, the development of a compression algorithm is proposed. As a result, an algorithm has been developed for compressing aerospace images for subsequent recognition and identification of various objects using wavelet transform for processing high- and medium-resolution space images when monitoring from remote sensing satellites, based on the use of structural features of object images. In particular, orthogonal and wavelet transforms are presented, adapted for compression of hyperspectral aerospace images with losses, an adaptive discrete cosine transform algorithm is presented, followed by quantization with a loss level and compression. Thanks to a series of experiments on hyperspectral aerospace images, the effectiveness of the proposed algorithm in terms of the degree of compression, as well as the characteristics of the limits of its applicability, can be highlighted. The use of wavelets provides progressive compression of the bitstream, which makes it possible to achieve lossless compression with minimal loss of information due to the modified Huffman algorithm with a compression ratio of 9 more than 2.5 times in existing algorithms, as well as the quality metric of the restored images, the peak signal-to-noise ratio is sufficiently below 32.56. The developed compression algorithm demonstrates the effectiveness of its application in terms of a set of characteristics and is superior to analogues. The scope and conditions for the practical use of the results obtained is a comparison of the proposed algorithm with the results of experiments obtained for universal compression algorithms for archivers and a compressor
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Cao, Han Xue, Si Yuan Long, and Hui Min Liao. "Compressive Deformation of Cast AM60B Mg Alloy at Elevated Temperatures." Materials Science Forum 546-549 (May 2007): 271–74. http://dx.doi.org/10.4028/www.scientific.net/msf.546-549.271.
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The deformability of cast AM60B Mg alloy is investigated by compressing AM60B cast ingots at elevated temperatures. The empirical results show that cast AM60B Mg alloy was brittle at room temperature and prone to cracking during compression, however at the temperatures ranging from 573 to 673K, excellent deformability is demonstrated with around 70% compression ratio. The compressive deformation constitutive equation for AM60B Mg alloy at elevated temperatures was established. The stress-strain relationships predicted at elevated temperatures show good agreement with experimental findings.
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Sazonov, I. A., M. A. Mokhov, Kh A. Tumanyan, M. A. Frankov, and S. I. Markelov. "Development of an Automated Compressor Unit for Gas Compression at the Periodic Connection of an Ejector." Journal of Computational and Theoretical Nanoscience 16, no. 12 (December 1, 2019): 5378–83. http://dx.doi.org/10.1166/jctn.2019.8586.
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The authors developed a new scientific approach for gas compression using ejector compressor units. A new patented technical solution opens up the prospect for the effective use of ejector compressor units when compressing various gases to pressures of 10…40 MPa. The goal of the research work is the development of automation systems using new scientific principles for gas compression. A new scientific approach is associated with the improvement of the ejector compressor unit, with the provision of conditions for the periodic connection of the ejector as part of the implementation of the cyclic low-frequency workflow. The results of scientific research can be used to create energy-efficient technologies for compressing and transferring various gases; it can be methane, associated petroleum gas, nitrogen, carbon dioxide, air, hydrogen or other gases. There is the prospect of using ejector compressors to create new internal combustion engines. Creating cheaper and more economical compressors will allow solving actual production problems in remote Arctic oil and gas fields.
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Lee, S. "Density ratios in compressions driven by radiation pressure." Laser and Particle Beams 6, no. 3 (August 1988): 597–606. http://dx.doi.org/10.1017/s026303460000553x.
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It has been recently suggested (Hora & Miley 1984) that in the cannonball scheme of laser compression the pellet may be considered to be compressed by the ‘brute force’ of the radiation pressure. For such a radiation-driven compression, this paper applies an energy balance method to give an equation fixing the radius compression ratio κ which is a key parameter for such intense compressions. A shock model is used to yield specific results. For a square-pulse driving power compressing a spherical pellet with a specific heat ratio of 5/3, a density compression ratio Γ of 27 is computed. Double (stepped) pulsing with linearly rising power enhances Γ to 1750. The value of Γ is not dependent on the absolute magnitude of the piston power, as long as this is large enough. Further enhancement of compression by multiple (stepped) pulsing becomes obvious. The enhanced compression increases the energy gain factor G for a 100 μm DT pellet driven by radiation power of 1016 W from 6 for a square pulse power with 0·5 MJ absorbed energy to 90 for a double (stepped) linearly rising pulse with absorbed energy of 0·4 MJ assuming perfect coupling efficiency.
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Darmawan, Rendi Editya, Untung Sujianto, and Nana Rochana. "Implementation of Chest Compression for Cardiac Arrest Patient in Indonesia: True or False." Jurnal Ners 16, no. 1 (January 19, 2021): 13. http://dx.doi.org/10.20473/jn.v16i1.17508.
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Introduction: The highest cause of death is cardiac arrest. Proper manual chest compression will increase survival of cardiac arrest. The aim of this study was to know the implementation of chest compressions for cardiac arrest patient in Indonesia.Methods: This study used a descriptive quantitative design. The samples were nurse and code blue team when performing manual chest compression to 74 patients experiencing cardiac arrest. The sample have body mass index (BMI) > 20. Research was conducted in two hospitals in Java, Indonesia. Implementation of chest compression is measured based on depth accuracy. Depth accuracy of chest compressions was assessed based on the comparison of the number of R waves with a height >10 mV on the bedside monitor with the number of chest compressions performed. The data were analyzed descriptively (mean, median, mode, standard deviation, and variances).Results: Result of this study is the mean of accuracy of compression depth is 75.97%. The result shows accuracy of compression depth on manual chest compression still under the American Heart Association (AHA) recommendation of 80%, because chest compression rate are not standardized. Chest compression rates are between 100-160 rates/minute, while AHA’s recommendations are 100-120 rates/minute. High compression speed causes a decrease in accuracy of chest compressions depth.Conclusion: In conclusion, the implementation of chest compressions in Indonesia if measured based on accuracy of compression depth is not effective. Nurses and the code blue team have to practice considering the use of cardiac resuscitation aids.
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Xu, Haoran, Petr M. Anisimov, Bruce E. Carlsten, Leanne D. Duffy, Quinn R. Marksteiner, and River R. Robles. "X-ray Free Electron Laser Accelerator Lattice Design Using Laser-Assisted Bunch Compression." Applied Sciences 13, no. 4 (February 10, 2023): 2285. http://dx.doi.org/10.3390/app13042285.
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We report the start-to-end modeling of our accelerator lattice design employing a laser-assisted bunch compression (LABC) scheme in an X-ray free electron laser (XFEL), using the proposed Matter-Radiation Interactions in Extremes (MaRIE) XFEL parameters. The accelerator lattice utilized a two-stage bunch compression scheme, with the first bunch compressor performing a conventional bulk compression enhancing the beam current from 20 A to 500 A, at 750 MeV. The second bunch compression was achieved by modulating the beam immediately downstream of the first bunch compressor by a laser with 1-μm wavelength in a laser modulator, accelerating the beam to the final energy of 12 GeV, and compressing the individual 1-μm periods of the modulated beam into a sequence of microbunches with 3-kA current spikes by the second bunch compressor. The LABC architecture presented had been developed based on the scheme of enhanced self-amplified spontaneous emission (ESASE), but operated in a disparate regime of parameters. Enabled by the novel technology of the cryogenic normal conducting radiofrequency photoinjector, we investigated an electron beam with ultra-low emittance at the starting point of the lattice design. Our work aimed at mitigating the well-known beam instabilities to preserve the beam emittance and suppress the energy spread growth.
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Meinich-Bache, Øyvind, Kjersti Engan, Tonje Søraas Birkenes, and Helge Myklebust. "Real-Time Chest Compression Quality Measurements by Smartphone Camera." Journal of Healthcare Engineering 2018 (October 28, 2018): 1–12. http://dx.doi.org/10.1155/2018/6241856.
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Out-of-hospital cardiac arrest (OHCA) is recognized as a global mortality challenge, and digital strategies could contribute to increase the chance of survival. In this paper, we investigate if cardiopulmonary resuscitation (CPR) quality measurement using smartphone video analysis in real-time is feasible for a range of conditions. With the use of a web-connected smartphone application which utilizes the smartphone camera, we detect inactivity and chest compressions and measure chest compression rate with real-time feedback to both the caller who performs chest compressions and over the web to the dispatcher who coaches the caller on chest compressions. The application estimates compression rate with 0.5 s update interval, time to first stable compression rate (TFSCR), active compression time (TC), hands-off time (TWC), average compression rate (ACR), and total number of compressions (NC). Four experiments were performed to test the accuracy of the calculated chest compression rate under different conditions, and a fifth experiment was done to test the accuracy of the CPR summary parameters TFSCR, TC, TWC, ACR, and NC. Average compression rate detection error was 2.7 compressions per minute (±5.0 cpm), the calculated chest compression rate was within ±10 cpm in 98% (±5.5) of the time, and the average error of the summary CPR parameters was 4.5% (±3.6). The results show that real-time chest compression quality measurement by smartphone camera in simulated cardiac arrest is feasible under the conditions tested.
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Messere, Alessandro, Gianluca Ceravolo, Walter Franco, Daniela Maffiodo, Carlo Ferraresi, and Silvestro Roatta. "Increased tissue oxygenation explains the attenuation of hyperemia upon repetitive pneumatic compression of the lower leg." Journal of Applied Physiology 123, no. 6 (December 1, 2017): 1451–60. http://dx.doi.org/10.1152/japplphysiol.00511.2017.
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The rapid hyperemia evoked by muscle compression is short lived and was recently shown to undergo a rapid decrease even in spite of continuing mechanical stimulation. The present study aims at investigating the mechanisms underlying this attenuation, which include local metabolic mechanisms, desensitization of mechanosensitive pathways, and reduced efficacy of the muscle pump. In 10 healthy subjects, short sequences of mechanical compressions ( n = 3–6; 150 mmHg) of the lower leg were delivered at different interstimulus intervals (ranging from 20 to 160 s) through a customized pneumatic device. Hemodynamic monitoring included near-infrared spectroscopy, detecting tissue oxygenation and blood volume in calf muscles, and simultaneous echo-Doppler measurement of arterial (superficial femoral artery) and venous (femoral vein) blood flow. The results indicate that 1) a long-lasting (>100 s) increase in local tissue oxygenation follows compression-induced hyperemia, 2) compression-induced hyperemia exhibits different patterns of attenuation depending on the interstimulus interval, 3) the amplitude of the hyperemia is not correlated with the amount of blood volume displaced by the compression, and 4) the extent of attenuation negatively correlates with tissue oxygenation ( r = −0,78, P < 0.05). Increased tissue oxygenation appears to be the key factor for the attenuation of hyperemia upon repetitive compressive stimulation. Tissue oxygenation monitoring is suggested as a useful integration in medical treatments aimed at improving local circulation by repetitive tissue compression. NEW & NOTEWORTHY This study shows that 1) the hyperemia induced by muscle compression produces a long-lasting increase in tissue oxygenation, 2) the hyperemia produced by subsequent muscle compressions exhibits different patterns of attenuation at different interstimulus intervals, and 3) the extent of attenuation of the compression-induced hyperemia is proportional to the level of oxygenation achieved in the tissue. The results support the concept that tissue oxygenation is a key variable in blood flow regulation.
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SHIMIZU, ICHIRO, NAOYA TADA, and KOSUKE NAKAYAMA. "THE INFLUENCE OF STRAIN PATH ON BIAXIAL COMPRESSIVE BEHAVIOR OF AZ31 MAGNESIUM ALLOY." International Journal of Modern Physics B 22, no. 31n32 (December 30, 2008): 5844–49. http://dx.doi.org/10.1142/s0217979208051261.
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The strain path dependence of the compressive flow behavior of cast AZ31 magnesium alloy was investigated. Biaxial compression tests with linear strain paths were conducted using a unique biaxial compression device. It was found that the equivalent stress-strain relations varied according to the strain paths. The work contour for linear strain paths was well described by the Logan-Hosford yield criterion. Biaxial compressions with abrupt strain path change were also carried out to investigate the influences of the prestrain amplitude and angular relation of the sequential strain paths on the flow behavior. Rapid increase in the equivalent stress was observed just after the abrupt strain path change. These specific flow behaviors were discussed with regard to the plastic anisotropy, which showed rapid evolution in the early stage of the biaxial compressions.
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Glukhov, Gennadiy Vasilyevich. "Linguistic compression at the level of word formation in English economic discourse." Philology. Issues of Theory and Practice 17, no. 7 (July 29, 2024): 2512–17. http://dx.doi.org/10.30853/phil20240357.
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The purpose of the study is to identify the features of the structure and semantics of word-formation compressions in English economic discourse. Clarifying the meaning of the term "linguistic compression" gives the author the opportunity to determine the means of expressing compression at the word-formation level in the economic sphere. The research has a scientific novelty, which consists in the fact that as a result of the first comprehensive analysis of the means of compressive word formation in English economic discourse, productive word-formation models were identified and described, as well as the originality of their structure and content was determined. As a result of the study, the predominance of models of compressive word formation formed by word composition was revealed, among which the uncomplicated N + N model, the substantive conversion model V + Prep (Adv), complex phrasal words (collapsed linguistic units) and compound words. It is noted that abbreviation in English economic discourse is a fairly effective way to implement linguistic compression due to the fact that it is characterized by the highest degree of compression. The predominant are initial three-component abbreviations with a substantial basic component, truncated syllabic type abbreviations (apocopa) and graphic abbreviations, characterized by rich semantic content in combination with a compressed form of expression.
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Goyal, V. K., A. K. Fletcher, and S. Rangan. "Compressive Sampling and Lossy Compression." IEEE Signal Processing Magazine 25, no. 2 (March 2008): 48–56. http://dx.doi.org/10.1109/msp.2007.915001.
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Zamfirescu, Calin. "MODELING AND OPTIMIZATION OF AN AMMONIA-WATER COMPRESSION-RESORPTION HEAT PUMPS WITH WET COMPRESSION." Transactions of the Canadian Society for Mechanical Engineering 33, no. 1 (March 2009): 75–88. http://dx.doi.org/10.1139/tcsme-2009-0008.
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Wet ammonia-water compression-resorption heat pumps constitute an attractive alternative to the commonly known heat pumps based on Osenbrück cycle because they eliminate the necessity of oil-liquid refrigerant separation. In this respect, a special designed oil-free compressor operating under wet (two-phase) conditions equips the heat pump. The compressor is lubricated by the liquid refrigerant which is carried-out while compressing the vapor. The thermodynamic cycle is located completely inside the two-phase region. In this paper are demonstrated two procedures to optimize the design for COP maximization. It is shown that there is: (i) an optimal choice of the vapor quality at suction, and (ii) an optimal distribution of heat transfer surface between the resorber and the desorber (the total amount of heat transfer surface, being an expression of investment cost, is fixed). The circulating concentration of ammonia has to be chosen such that the minimum pressure in the system is over one bar (to avoid air penetration from the atmosphere) and the maximum pressure is bounded by a technical-economical maximal limit. A general procedure for calculation of the optimal cycle parameters is presented and exemplified for a case with practical relevance. The paper presents only the trends and rough quantitative estimations because the analyzed case is restricted to the ideal isentropic compression. Further research is needed to quantify in detail the effect of compression irreversibility.
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Kim, Kyoung Hoon, and Chul Ho Han. "Performance Analysis of Wet Compression Process under Critical Conditions of Water Injection." Applied Mechanics and Materials 229-231 (November 2012): 2541–45. http://dx.doi.org/10.4028/www.scientific.net/amm.229-231.2541.
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In wet compression process water is injected at an inlet of compressor and continuous cooling occurs due to evaporation of water droplets during the compression process of air, which can save the compression work and enhance the performance of gas turbine system. In this work, performance analysis of the wet compression process is carried out under the critical conditions of water injection which are defined as the maximum water injection which can be evaporated completely inside the compressor. For various ambient conditions the important variables of wet compression process such as water injection ratio, temperature-averaged polytropic coefficient, compressor outlet temperature, and compression work are estimated under the critical injection conditions. Parametric studies show that compression work decreases with ambient temperature, however, the reduction ratio of compression work relative to dry increases with ambient temperature.
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Ji, Guang Kai, Xiao Liu, and Zhao Qun Du. "Analysis on Plane and Ball Compression Behaviour of Spacer Fabric." Advanced Materials Research 332-334 (September 2011): 1049–52. http://dx.doi.org/10.4028/www.scientific.net/amr.332-334.1049.
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In present paper, the compression force and strain curve for both plane plate and spherical ball compressions are conducted, where the compression stress and strain curve in plane plate compression is calculated and divided into three linear sections. Each linear region has corresponding compression modulus. In addition, three compression characters of both plate plane and spherical ball compressions are featured as compression work, maximum pressure/force and linear degree. Correlations between the three characters of compression property show that there exist high correlations between compression work and maximum pressure/force for plane plated and spherical ball compression. Moreover, effects of sample size and shape on compression properties are also conducted, and we find that there are no significant effects and the three compression characters are stable in both plane plate and spherical ball compression. Finally, the explicit formula derived in the Part I of this series for the spherical ball compression is used, and the ball compression force and strain curves are simulated based on the compression stress and strain curves based on plane plate compression tests. The comparing results between measured and theoretical results indicate that the theoretical model is effective to simulate ball compression behaviour of general knitted spacer fabrics. It is highly helpful in designing and predicting compression force of knitted spacer fabric for virtual processing of textile materials.
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Shin, So-Yeon. "Analysis and Improvement Plan of Chest Compression and Ventilation during Transport." Fire Science and Engineering 36, no. 4 (August 31, 2022): 51–57. http://dx.doi.org/10.7731/kifse.0ec41f56.
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This study aimed to compare the outcomes of manual and automated chest compressions during virtual reality (VR)-based ambulance transport and measure the ventilation and airway pressure provided by different types of portable positive pressure ventilation in the national fire academy. The chest compression depths were 53.78 mm and 49.01 mm for automated and manual chest compressions, respectively, showing that automated chest compression achieved the appropriate compression depth. The compression rates were 101.8 times per min and 122.6 times per min for automated and manual compressions, respectively; however, the manual compression rate was irregular, ranging from 54∼178 times per min. The amounts of ventilation delivered by the portable positive pressure ventilator were 427.01 ml, 302.87 ml and 455.67 ml for models 1, 2 and 3, respectively, showing that models 1 and 3 delivered the appropriate amounts of ventilation. Therefore, automated chest compression is effective regarding compression depth and rate, incomplete release and release rate, hands-off time and compression site during VR-based patient transport. Portable positive pressure ventilators are easy to apply and can be used during patient transport; however, the ventilation varies according to the type used.
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WU, JOHN Z., REN G. DONG, W. PAUL SMUTZ, and AARON W. SCHOPPER. "EFFECTS OF PRECONDITIONING ON THE ELASTIC BEHAVIOR OF SKIN UNDER COMPRESSIVE LOADING." Journal of Mechanics in Medicine and Biology 03, no. 03n04 (September 2003): 275–83. http://dx.doi.org/10.1142/s0219519403000788.
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In physiological loading conditions, the skin tissues are, sometimes, loaded compressively. The mechanical characteristics of skins in tension have been studied intensively, while those in compression have not been studied thoroughly. Previous studies suggested that, in order to obtain repeatable mechanical parameters, the skin sample should be properly preconditioned in the tensile tests. The present study is to investigate if the skin sample should be preconditioned in the compressive tests. Pigskins were used in the present study. Compression tests were performed in confined and unconfined loading configurations and at four different loading speeds (0.5, 1.0, 40, and 400 μm/s). Our results show that skin samples should be preconditioned in compressive tests, to obtain repeatable mechanical parameters. The necessary number of the loading cycles in the preconditioning treatment for compressive testing is less than that for tensile testing. Our findings indicate that the skin samples reach repeatable mechanical behavior after 3–4 loading cycles, independent of the loading rate and loading configurations (confined or unconfined compressions).
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Khazanov, E. A., Sergei Yu Mironov, and Gérard Mourou. "Nonlinear compression of high-power laser pulses: compression after compressor approach." Uspekhi Fizicheskih Nauk 189, no. 11 (May 2019): 1173–200. http://dx.doi.org/10.3367/ufnr.2019.05.038564.
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Khazanov, E. A., S. Yu Mironov, and G. A. Mourou. "Nonlinear compression of high-power laser pulses: compression after compressor approach." Physics-Uspekhi 62, no. 11 (November 30, 2019): 1096–124. http://dx.doi.org/10.3367/ufne.2019.05.038564.
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JAMES, BRYONY, and CELIA FONSECA. "TEXTURE STUDIES AND COMPRESSION BEHAVIOUR OF APPLE FLESH." International Journal of Modern Physics B 20, no. 25n27 (October 30, 2006): 3993–98. http://dx.doi.org/10.1142/s021797920604074x.
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Compressive behavior of fruit flesh has been studied using mechanical tests and microstructural analysis. Apple flesh from two cultivars (Braeburn and Cox's Orange Pippin) was investigated to represent the extremes in a spectrum of fruit flesh types, hard and juicy (Braeburn) and soft and mealy (Cox's). Force-deformation curves produced during compression of unconstrained discs of apple flesh followed trends predicted from the literature for each of the "juicy" and "mealy" types. The curves display the rupture point and, in some cases, a point of inflection that may be related to the point of incipient juice release. During compression these discs of flesh generally failed along the centre line, perpendicular to the direction of loading, through a barrelling mechanism. Cryo-Scanning Electron Microscopy (cryo-SEM) was used to examine the behavior of the parenchyma cells during fracture and compression using a purpose designed sample holder and compression tester. Fracture behavior reinforced the difference in mechanical properties between crisp and mealy fruit flesh. During compression testing prior to cryo-SEM imaging the apple flesh was constrained perpendicular to the direction of loading. Microstructural analysis suggests that, in this arrangement, the material fails along a compression front ahead of the compressing plate. Failure progresses by whole lines of parenchyma cells collapsing, or rupturing, with juice filling intercellular spaces, before the compression force is transferred to the next row of cells.
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Pan, Xi, Man Wang, Zi-wen Xing, and Shu-lin Pan. "Structural study on a swing compressor with no valves for air compression." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 232, no. 23 (December 27, 2017): 4390–98. http://dx.doi.org/10.1177/0954406217750188.
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This paper presents a novel swing compressor with no valves employed in air compression. The design and work principle of this swing compressor are introduced. And the effects of discharge port, exhaust cavity, and crank speed on the performances of this compressor are analyzed. Under the same operating conditions and dimensions, the size of exhaust cavity mainly depends on the discharge port width. Additionally, the exhaust cavity angle has a direct impact on the compression process, whether it is over-compression or under-compression. And the over-compression loss can be designed below 2%. Overall, the assessment of the structure shows that this novel swing compressor with no valves has the advantages of simple component geometries, light weight, and high efficiency, which makes it well suited to the requirements of air compression.
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Gindl, W. "Comparing Mechanical Properties of Normal and Compression Wood in Norway Spruce: The Role of Lignin in Compression Parallel to the Grain." Holzforschung 56, no. 4 (June 27, 2002): 395–401. http://dx.doi.org/10.1515/hf.2002.062.
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Summary Cell-wall lignin content and composition, as well as microfibril angle of normal and compression wood samples were determined prior to mechanical testing in compression parallel to the grain. No effect of increased lignin content on the Young's modulus in compression wood was discernible because of the dominating influence of microfibril angle. In contrast, compressive strength of compression wood was not negatively affected by the high microfibril angle. It is proposed that the observed high lignification in compression wood increases the resistance of the cell walls to compression failure. An increased percentage of p-hydroxyphenylpropane units observed in compression wood lignin may also contribute to the comparably high compressive strength of compression wood.
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Viguié, Jeremie, P. J. J. Dumont, P. Vacher, Laurent Orgéas, I. Desloges, and E. Mauret. "Analysis of the Strain and Stress Fields of Cardboard Box during Compression by 3D Digital Image Correlation." Applied Mechanics and Materials 24-25 (June 2010): 103–8. http://dx.doi.org/10.4028/www.scientific.net/amm.24-25.103.
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Corrugated boards with small flutes appear as good alternatives to replace packaging folding boards or plastic materials due their small thickness, possibility of easy recycling and biodegradability. Boxes made up of these materials have to withstand significant compressive loading conditions during transport and storage. In order to evaluate their structural performance, the box compression test is the most currently performed experiment. It consists in compressing an empty container between two parallel plates at constant velocity. Usually it is observed that buckling phenomena are localized in the box panels, which bulge out during compression [1]. At the maximum recorded compression force, the deformation localises around the box corners where creases nucleate and propagate. This maximum force is defined as the quasi-static compression strength of the box. The prediction of such strength is the main topic of interest of past and current research works. For example, the box compression behaviour of boxes was studied by Mc Kee et al. [2] and Urbanik [3], who defined semi-empirical formula to predict the box compression strength, as well as by Beldie et al. [4] and Biancolini et al. [5] by finite element simulations. But comparisons of these models with experimental results remain rather scarce and limited.
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Lee, Jang Hee, Sang Kuk Han, and Ji Ung Na. "Current Guideline of Chest Compression Depth for Children of All Ages May Be Too Deep for Younger Children." Emergency Medicine International 2019 (June 19, 2019): 1–7. http://dx.doi.org/10.1155/2019/7841759.
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Aim. To determine whether the chest compression depth of at least 1/3 of the Anteroposterior (AP) diameter of the chest and about 5 cm is appropriate for children of all age groups via chest computed tomography. Methods. The AP diameter of the chest, anterior chest wall diameter, and compressible diameter (Cd) were measured at the lower half of the sternum for patients aged 1-18 years using chest computed tomography. The mean ratio of 5 cm compression to the Cd of adult patients was used as the lower limit, and the mean ratio of 6 cm compression to the Cd of adult patients was used as the upper limit. Also, the depth of chest compression resulting in a residual depth <1 cm was considered to cause internal injury potentially. With the upper and lower limits, the compression ratios to the Cd were compared when compressions were performed at a depth of 1/3 the AP diameter of the chest and 5 cm for patients aged 1-18 years. Results. Among children aged 1-7 years, compressing 5 cm was deeper than 1/3 the AP diameter. Also, among children aged 1-5 years, 5 cm did not leave a residual depth of 1 cm, potentially causing intrathoracic injury. Conclusion. Current pediatric resuscitation guidelines of chest compression depth for children were too deep for younger children aged 1-7 years.
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Boeva, E. A., D. O. Starostin, M. A. Milovanova, V. V. Antonova, D. Ch Kargin, and S. N. Abdusalamov. "Assessment of the Quality of Chest Compressions Performed by Health-Care Workers Under Simulated Conditions." General Reanimatology 17, no. 4 (August 27, 2021): 37–47. http://dx.doi.org/10.15360/1813-9779-2021-4-37-47.
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Aim of the study: to investigate chest compression parameters by city hospital staff under simulated conditions with and without the use of a sensor device for quality control of chest compressions.Materials and Methods. The study was conducted in Moscow's multidisciplinary hospitals. The study included 359 medical staff members. The participants were divided into 4 groups: physicians (n=97) and nurses (n=82) from intensive care units (ICU) and physicians (n=92) and nurses (n=88) from specialized departments. Participants performed 2 minutes of chest compressions without a chest compressions quality control (CCQC) sensor, followed by 2 minutes of chest compressions using a defibrillator sensor with audiovisual prompts from the device turned on. The percentage of target compressions, rate and depth of compressions were analyzed.Results. Compression parameters in the group of ICU doctors were outside the reference range (% target compression — 0.5 (0.0; 14.5)%, rate 124.1±17.8 per minute, depth 5.6±1.1 cm), in the group of ICU nurses, the percentage of target compressions was 0.0 (0.0; 3.5)%, rate — 123.6±23.7 per minute, depth — 5.3±1.2 cm, in the group of specialist doctors the percentage of target compressions was 0.0 (0.0; 1.2) %, rate — 123.8±23.2 per minute, depth — 5.8±1.2 cm, in specialized nurses group the percentage of target compressions was 0.0 (0.0; 6.1)%, rate — 119.7±29.5 per minute, depth — 5.6±1.2 cm. There was a significant improvement in compression performance in all groups when the sensor device was used: in ICU physicians the percentage of target compressions was 81.6 (64.80; 87.90)%, rate — 124.1±17.8 per minute, depth — 5.5±0.2 cm; in ICU nurses the percentage of target compressions was 69.1 (47.4; 80.6), rate — 123.6±23.7 per minute, depth — 5.3±0.3 cm, in specialist doctors the percentage of target compressions was 69.30 (50.50; 78.70), rate — 123.8±23.2 per minute, depth — 5.4±0.3 cm, in specialized nurses the percentage of target compressions reached 63.70 (42.90; 75.80), rate — 119.7±29.5 per minute, depth — 5.4±0.3 cm. There were no differences in analysed compression parameters between staff in different departments or positions.Conclusion. Compression parameters (percentage of target compressions, rate, depth) were not influenced by the department where the staff member worked and the position held (doctor or nurse). The use of a compression quality sensor device has improved compression parameters by reducing rate and normalizing depth. The use of the sensor does not increase the percentage of target compressions to the maximum values, indicating the need for training by an instructor.
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Lau, Tiffany Wai Shan, Anthony Robert Lim, Kyra Anne Len, and Loren Gene Yamamoto. "Chest compression efficacy of child resuscitators." Journal of Paramedic Practice 13, no. 11 (November 2, 2021): 448–55. http://dx.doi.org/10.12968/jpar.2021.13.11.448.
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Background: Chest compression efficacy determines blood flow in cardiopulmonary resuscitation (CPR) and relies on body mechanics, so resuscitator weight matters. Individuals of insufficient weight are incapable of generating a sufficient downward chest compression force using traditional methods. Aims: This study investigated how a resuscitator's weight affects chest compression efficacy, determined the minimum weight required to perform chest compressions and, for children and adults below this minimum weight, examine alternate means to perform chest compressions. Methods: Volunteers aged 8 years and above were enrolled to perform video-recorded, music-facilitated, compression-only CPR on an audible click-confirming manikin for 2 minutes, following brief training. Subjects who failed this proceeded to alternate modalities: chest compressions by jumping on the lower sternum; and squat-bouncing (bouncing the buttocks on the chest). These methods were assessed via video review. Findings: There were 57 subjects. The 30 subjects above 40kg were all able to complete nearly 200 compressions in 2 minutes. Success rates declined in those who weighed less than 40kg. Below 30 kg, only one subject (29.9 kg weight) out of 14 could achieve 200 effective compressions. Nearly all of the 23 subjects who could not perform conventional chest compressions were able to achieve effective chest compressions using alternate methods. Conclusion: A weight below 40kg resulted in a declining ability to perform standard chest compressions effectively. For small resuscitators, the jumping and squat-bouncing methods resulted in sufficient compressions most of the time; however, chest recoil and injuries are concerns.
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Tsutsumi, Satoshi, Hideo Ono, and Yukimasa Yasumoto. "Vascular Compression of the Anterior Optic Pathway: A Rare Occurrence?" Canadian Association of Radiologists Journal 68, no. 4 (November 2017): 409–13. http://dx.doi.org/10.1016/j.carj.2017.02.001.
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Background Vascular compression of the anterior optic pathway has been documented as an infrequent cause of visual impairments. Here we characterize such vascular compression using magnetic resonance imaging. Methods A total of 183 patients without pathologies affecting the optic pathways underwent T2-weighted or constructive interference steady-state sequence magnetic resonance imaging. Imaging data from coronal sections were analyzed. Results A vascular compression of the anterior optic pathway was identified in 20 patients (11%). They comprised 13 men and 7 women with a mean age of 60.8 years. The vascular compressions were observed at 22 sites, 15 on the optic nerve (ON) and 7 on the optic chiasm (OC). Twelve of them were on the right and 10 were on the left side. The offending vessels were the supraclinoid portion of the internal carotid artery in 86.4% and the A1 segment of the anterior cerebral artery in 13.6%. Compression sites at the ON and OC were variable, with the inferolateral surface being the most frequent (77.3% occurrences). In 2 patients (9.1%), the ON was compressed in a sandwich manner. Conclusions Vascular compression of the ON and OC may not be an infrequent occurrence in the cranial cavity. Progressive and unexplainable visual impairment might possibly be caused by vascular-compressive neuropathy.
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Wang, Yan Wei, and Hui Li Yu. "Wavelet Transforms of Image Reconstruction Based on Compressed Sampling." Applied Mechanics and Materials 58-60 (June 2011): 1920–25. http://dx.doi.org/10.4028/www.scientific.net/amm.58-60.1920.
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A compressive sensing technique for image signal to cope with image compression and restoration is adopted in this paper. First of all wavelet transforms method is applied in image compressing to preserve the constructive, Secondly, sparse matrix is available by required wavelet ratio. Thirdly, the compressing image is used to restoration the original image. Experimental results show that the proposed algorithm is effective and compares favorably with existing techniques.
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Chen, Xinyu, Jiannan Tian, Ian Beaver, Cynthia Freeman, Yan Yan, Jianguo Wang, and Dingwen Tao. "FCBench: Cross-Domain Benchmarking of Lossless Compression for Floating-Point Data." Proceedings of the VLDB Endowment 17, no. 6 (February 2024): 1418–31. http://dx.doi.org/10.14778/3648160.3648180.
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While both the database and high-performance computing (HPC) communities utilize lossless compression methods to minimize floating-point data size, a disconnect persists between them. Each community designs and assesses methods in a domain-specific manner, making it unclear if HPC compression techniques can benefit database applications or vice versa. With the HPC community increasingly leaning towards in-situ analysis and visualization, more floating-point data from scientific simulations are being stored in databases like Key-Value Stores and queried using in-memory retrieval paradigms. This trend underscores the urgent need for a collective study of these compression methods' strengths and limitations, not only based on their performance in compressing data from various domains but also on their runtime characteristics. Our study extensively evaluates the performance of eight CPU-based and five GPU-based compression methods developed by both communities, using 33 real-world datasets assembled in the Floating-point Compressor Benchmark (FCBench). Additionally, we utilize the roofline model to profile their runtime bottlenecks. Our goal is to offer insights into these compression methods that could assist researchers in selecting existing methods or developing new ones for integrated database and HPC applications.
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Yin, Yu Ting, Lian Yong Wang, and Jiu Ju Cai. "Study on Influence Factors to the Biomass Compression Process." Applied Mechanics and Materials 71-78 (July 2011): 2939–43. http://dx.doi.org/10.4028/www.scientific.net/amm.71-78.2939.
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The principle of biomass briquetting, the advantages and disadvantages of biomass briquette machine and the current research status were introduced in this paper. The influence of the four factors biomass particle size, moisture, pressure and compression speed to formation density and compressive strength was summarized, by orthogonal test method. The results show that, the influence of biomass size to the formation density is largest and to the compressive strength is least. The biomass size in the range of<40 mesh is best. The influence of compressing speed to compressive strength is largest and to formation density is least. The speed about 60mm/min is best. The influence of biomass moisture content and pressure cannot be neglected, 15% and 10MPa are best in this paper.
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Zubaidah, Isa, Abdullah Norfatriah, Serbini Zatul Amali, and Abu Zuruzi. "Preparation and Behavior of Bamboo Fiber-Reinforced Polydimethylsiloxane Composite Foams during Compression." Fibers 6, no. 4 (November 29, 2018): 91. http://dx.doi.org/10.3390/fib6040091.
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This study investigates the mechanical properties of bamboo fiber-reinforced polydimethylsiloxane (BF-PDMS) foams with up to 3.4% (by mass) fiber during compression. Pristine PDMS foams and BF-PDMS composite foams were fabricated using a sugar leaching method. Compression test results of pristine PDMS and BF-PDMS composite foams display plateau and densification regions. Predictions of a modified phenomenological foam (PF) model based on Maxwell and Kelvin–Voight models are in good agreement with compression test results. Stiffness coefficients were extracted by fitting results of compression tests to the modified PF model. Spring and densification coefficients of BF-PDMS composite foams are 2.5- and 15-fold greater than those of pristine PDMS foams, respectively. Strains corresponding to onset of densification computed using extracted coefficients were 35% and 25% for pristine PDMS foams and BF-PDMS composite foams, respectively. Compressing foams at 6.0 and 0.5 mm/min results in highest and lowest compressive stress, respectively. Insights from this study are useful in many areas such as environmental protection, pressure sensing, and energy where PDMS composite foams will find applications.
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Liu, Chunlei, Qun Zheng, Qi Wang, Aqiang Lin, Yuting Jiang, and Mingcong Luo. "Sensitivity Analysis of Multistage Compressor Characteristics Under the Spray Atomization Effect Using a CFD Model." Energies 12, no. 2 (January 18, 2019): 301. http://dx.doi.org/10.3390/en12020301.
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In this paper, a CFD model is used to simulate the effect of spray atomization at the compressor inlet on a multistage axial subsonic compressor. Special attention is paid to the change of compressor characteristics with wet compression under different rotating speeds to gain the compressor characteristic lines of wet compression. The effects of pneumatic crushing and blade-wall-collision on water droplets and droplet trajectories are contrasted and analyzed under different spray conditions. Then, the whole/stage-by-stage compressor performances and the flow field are also investigated under dry and wet cases near the design operating condition. The results indicate that multistage compressor performance can be improved with wet compression under the proper water spaying rate and a small droplet size. The influence of pneumatic crushing on the water droplets below 20 μm can be ignored, and the effect of blade collision on water droplets above 5μm should be considered in the wet compression conditions. Compared to the dry compression, as measured by volume flow, wet compression with proper spaying conditions makes the front stages operate within a relatively high flow range and the back stages operate within a relatively low flow range. Additionally, the operating state with wet compression is opposite to the compressor operating near the surge boundary, which presents the phenomenon of “former surged and back blocking”.
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Peer, Syed Murfad, Syed Bukhari, Manan Desai, Aybala Tongut, Anthony Ho, Can Yerebakan, Karthik Ramakrishnan, et al. "Compression Device-Assisted Extracorporeal Cardiopulmonary Resuscitation Cannulation in Pediatric Patients—A Simulation Study." World Journal for Pediatric and Congenital Heart Surgery 13, no. 3 (April 21, 2022): 379–82. http://dx.doi.org/10.1177/21501351221084304.
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Background: Surgical neck cannulation for pediatric extracorporeal cardiopulmonary resuscitation (ECPR) requires multiple interruptions of manual chest compressions to facilitate the procedure. Effective uninterrupted CPR is essential to prevent neurological injury. We hypothesized that an automated chest compression device can be used to provide effective and uninterrupted chest compressions during pediatric neck ECPR cannulation. The feasibility of surgically cannulating the right carotid artery and right internal jugular vein in an infant during ongoing automated chest compressions was tested in a simulation study. Methods: A working prototype of a pediatric chest compression device was designed to provide automated chest compressions on an infant CPR manikin at the rate of 120 compressions/minute. A feedback device attached to the manikin was used to monitor the effectiveness of CPR. A synthetic artery, vein along with carotid sheath and skin was utilized to simulate surgical neck exploration. ECPR simulation was conducted using the compression device to provide chest compressions. Results: Four ECPR simulations were conducted during which vessel sparing (n = 2) and non-vessel sparing (n = 2) cannulation of the right internal carotid artery and right internal jugular vein were performed during ongoing mechanical chest compressions. All four cannulations were successfully performed without the need to interrupt chest compressions. Conclusions: In a simulated environment, pediatric ECPR neck cannulation with uninterrupted chest compressions may be accomplished using an automated chest compression device. The strategy of compression device-assisted ECPR cannulation requires further study and could potentially reduce the neurological complications of ECPR.
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Tang, Hao, Chiyang Liu, Nianqin Wang, Huahua Li, Guannan Wu, Jinzhi Luo, and Mengli Zeng. "Influence of Acidic Substances on Compression Deformation Characteristics of Loess." Advances in Civil Engineering 2021 (April 20, 2021): 1–12. http://dx.doi.org/10.1155/2021/6614391.
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Current research theories on acid-contaminated soils indicate that acids can alter the physical properties of soils, which in turn can affect their engineering mechanical properties. However, compressibility, one of the most important mechanical properties of loess, may be affected by acidic substances. To investigate the influence of acid on the compression properties of loess, this study uses a uniaxial compressor to investigate the changes of compression properties of loess under different acid concentrations and different acid immersion times and attempts to predict the causes of macroscopic compressibility changes from the microscopic pore changes of acid-etched loess. The test results show that when the soaking time is the same, the hydrochloric acid concentration increases from 0 to 3.0 mol/L, the compression coefficient Cc increases by 43.20–87.5%, and the compression yield stress σpc decreases by 51.36–60.86%; when the concentration of hydrochloric acid is the same, the soaking time increases from 1 day to 12 days, the compression coefficient Cc increases by 119.05–197.46%, and compressive yield stress σpc decreases by 10.67–22.02%. The microscopic images of loess soaked for 12 days at 3.0 mol/L hydrochloric acid concentration were compared with those of the original loess. The percentages of micropore, small pore, mesopore, and macropore areas of original loess were 20.90%, 79.10%, 0%, and 0%, respectively. The percentages of micropore, small pore, mesopore, and macropore areas of acid-etched loess were 6.24%, 37.21%, 1.14%, and 55.40%, respectively. The enhancement of the compressive properties of acid-etched loess is the result of the coupling of acid concentration and soaking time, and the change of macroscopic compressive properties may be related to the increase of microscopic macropore area after acid erosion. The results of this study can be used as a reference for the study of soil mechanical properties in acid-contaminated soils.
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Gibbons Kroeker, Carol A., Samer Adeeb, Nigel G. Shrive, and John V. Tyberg. "Compression induced by RV pressure overload decreases regional coronary blood flow in anesthetized dogs." American Journal of Physiology-Heart and Circulatory Physiology 290, no. 6 (June 2006): H2432—H2438. http://dx.doi.org/10.1152/ajpheart.01140.2005.
Full textAbstract:
Pulmonary artery constriction (PAC), a model of right ventricular (RV) pressure overload, flattens or inverts the septum and may flatten the left ventricular (LV) free wall. Finite element (FE) analysis predicts that such deformations may cause substantial compression. This study tests the hypothesis that deformation-induced myocardial compressive stress impedes coronary blood flow (CBF). Colored microspheres (∼2 × 106) were injected into the left atrium of 13 open-chest, anesthetized dogs under control conditions and during PAC, which decreased the end-diastolic transseptal pressure gradient (LV − RV) from 1.6 ± 1.3 to −3.4 ± 1.7 mmHg. Septal and LV deformation was assessed with the use of two-dimensional echocardiography, and by FE analysis, the hydrostatic component of stress was assessed. Postmortem, a 2.5-cm wide, LV equatorial ring was divided into 16 endocardial and epicardial samples. PAC decreased CBF in the FE-predicted compression zones, areas with the greatest compression having the greatest reductions in CBF. During PAC, compression reached a maximum of 25.3 ± 1.8 mmHg on the (LV) endocardial sides of the RV insertion points, areas that saw CBF decrease from 1.05 ± 0.08 to 0.68 ± 0.05 ml·min−1·g−1 ( P < 0.001), more than 30%. CBF decreased (from 1.08 ± 0.07 to 0.81 ± 0.07 ml·min−1·g−1; P < 0.001) on the RV side of the midseptum, an area with as much as 16.0 ± 1.0 mmHg of compression. Overall, average compressions of 10 mmHg decreased CBF by ∼30%. We conclude that acute RV pressure overload deforms the septum and LV and induces compressive stresses that reduce CBF substantially. This may help explain why some patients with pulmonary hypertension and no critical coronary disease have chest discomfort indistinguishable from angina pectoris.
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Kang, Hyun-Su, Sung-Yeon Kim, and Youn-Jea Kim. "Wet Compression Study for an Aero-Thermodynamic Performance Analysis of a Centrifugal Compressor at Design and Off-Design Points." Processes 10, no. 5 (May 9, 2022): 936. http://dx.doi.org/10.3390/pr10050936.
Full textAbstract:
In this study, to analyze the effect of wet compression technology on the aero-thermodynamic performance of a centrifugal compressor, a numerical analysis study was conducted on the design point and off-design point. Wet compression technology sprays water droplets at the inlet of the compressor. During the compression process, water droplets evaporate, reducing the heat of compression and reducing the compression work, which improves the efficiency of the compressor. In wet compression technology, detailed research is needed for the application to compressors because the droplet behavior affects the internal flow. The main parameters for wet compression technology are the droplet size and injection rate selection, and the flow inside the compressor changed by the droplet behavior was analyzed. When the droplet size and injection rate were changed at the design point and the off-design point, it was confirmed that a small droplet size was effective in both areas, and it was confirmed that the performance improved as the flow rate increased. The internal flow changed greatly depending on the size of the droplet. As a result, the centrifugal compressor to which the wet compression technology was applied had a lower outlet temperature than dry compression at both the design point and the off-design point and had increases in the pressure ratio and efficiency. However, the surge margin decreased by about 2% in the surge region. The reason is that due to high-speed rotation, particles move in the outer diameter direction and are driven into a tip-leakage flow, and many stagnant flows occur without flowing into the main flow. Through the study results, it was possible to understand the effects of wet compression technology on the performance and efficiency increase of centrifugal compressors and the effects of particle behavior on the internal flow of the compressor at the off-design point.