Готові списки джерел за темами / Low Density Spreading

Добірка наукової літератури з теми "Low Density Spreading"

Автор: Grafiati

Опубліковано: 14 березня 2023

Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями

Оберіть тип джерела:

Зміст

Статті в журналах
Дисертації
Частини книг
Тези доповідей конференцій

Ознайомтеся зі списками актуальних статей, книг, дисертацій, тез та інших наукових джерел на тему "Low Density Spreading".

Біля кожної праці в переліку літератури доступна кнопка «Додати до бібліографії». Скористайтеся нею – і ми автоматично оформимо бібліографічне посилання на обрану працю в потрібному вам стилі цитування: APA, MLA, «Гарвард», «Чикаго», «Ванкувер» тощо.

Також ви можете завантажити повний текст наукової публікації у форматі «.pdf» та прочитати онлайн анотацію до роботи, якщо відповідні параметри наявні в метаданих.

Статті в журналах з теми "Low Density Spreading"

Chen, Shuang, Kewu Peng, Yushu Zhang, and Jian Song. "Performance evaluation of low-density spreading multiple access." IET Communications 13, no. 1 (January 4, 2019): 108–15. http://dx.doi.org/10.1049/iet-com.2018.5310.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Le, Mai T. P., Guido Carlo Ferrante, Tony Q. S. Quek, and Maria-Gabriella Di Benedetto. "Fundamental Limits of Low-Density Spreading NOMA With Fading." IEEE Transactions on Wireless Communications 17, no. 7 (July 2018): 4648–59. http://dx.doi.org/10.1109/twc.2018.2828853.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Al-Imari, Mohammed, Muhammad Ali Imran, and Pei Xiao. "Radio Resource Allocation for Multicarrier Low-Density-Spreading Multiple Access." IEEE Transactions on Vehicular Technology 66, no. 3 (March 2017): 2382–93. http://dx.doi.org/10.1109/tvt.2016.2579168.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Millar, Goldwyn, Michel Kulhandjian, Ayse Alaca, Saban Alaca, Claude D'Amours, and Halim Yanikomeroglu. "Low-Density Spreading Design Based on an Algebraic Scheme for NOMA Systems." IEEE Wireless Communications Letters 11, no. 4 (April 2022): 698–702. http://dx.doi.org/10.1109/lwc.2022.3140223.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Jiroušková, Markéta, Jyoti K. Jaiswal та Barry S. Coller. "Ligand density dramatically affects integrin αIIbβ3-mediated platelet signaling and spreading". Blood 109, № 12 (15 червня 2007): 5260–69. http://dx.doi.org/10.1182/blood-2006-10-054015.

Повний текст джерела

Анотація:

Abstract The impact of ligand density on integrin-mediated cell adhesion and outside-in signaling is not well understood. Using total internal reflection fluorescent microscopy, conformation-specific antibodies, and Ca2+ flux measurements, we found that the surface density of fibrinogen affects αIIbβ3-mediated platelet signaling, adhesion, and spreading. Adhesion to fibrinogen immobilized at low density leads to rapid increases in cytosolic Ca2+ and sequential formation of filopodia and lamellipodia. In contrast, adhesion to high-density fibrinogen results in transient or no increases in Ca2+ and simultaneous formation of filopodia and lamellipodia. αIIbβ3 receptors at the basal surface of platelets engage fibrinogen in a ringlike pattern at the cell edges under both conditions. This engagement is, however, more dynamic and easily reversed on high-density fibrinogen. Src and Rac activity and actin polymerization are important for adhesion to low-density fibrinogen, whereas PKC/PI3 kinases contribute to platelet spreading on high-density fibrinogen. We conclude that 2 fundamentally different signaling mechanisms can be initiated by a single integrin receptor interacting with the same ligand when it is immobilized at different densities.

Стилі APA, Harvard, Vancouver, ISO та ін.

Li, Y. L. "Interfacial Wetting Behavior under Low-Density Ultrasonic Field and Solvent - Assisted Wet Condition." Advanced Materials Research 1015 (August 2014): 458–62. http://dx.doi.org/10.4028/www.scientific.net/amr.1015.458.

Повний текст джерела

Анотація:

In this paper, the author had adopted the low-density ultrasonic field coupling method, coupled the ultrasonic directional beam to metallic melt, and then coupled energy to C/Al interface by sound propagation, eventually accomplish C/Al interfacial wettability and interfacial reaction by using ultrasonic field coupling method, and synthesize Al-Ti-C master alloys by using the same method. Some experiments showed that in the low-density ultrasonic field and under flux auxiliary wetting, there is no explicit incubation period in the prophase of wetting, in the medium term of wetting, the wetting angle between aluminum melt and carbon will reduce with time extension, however, the wetting spreading radius will increase with the extended holding time, and reach wetting balance state in 20 minutes. In the condition of 1023K, the equilibrium wetting angle is less than 22°,and wetting spreading radius is close to 20mm.

Стилі APA, Harvard, Vancouver, ISO та ін.

Gao, A. G., F. P. Lindberg, J. M. Dimitry, E. J. Brown, and W. A. Frazier. "Thrombospondin modulates alpha v beta 3 function through integrin-associated protein." Journal of Cell Biology 135, no. 2 (October 15, 1996): 533–44. http://dx.doi.org/10.1083/jcb.135.2.533.

Повний текст джерела

Анотація:

Integrin-associated protein (IAP) is a receptor for the carboxyl-terminal "cell-binding domain" (CBD) of thrombospondin 1 (TS1). IAP associates with alpha v beta 3 integrin and mAbs against IAP inhibit certain integrin functions. Here we examine the effects of the TS1 CBD and 4N1K (KRFYVVMWKK), a cell-binding peptide derived from it, on the adhesion and spreading on vitronectin (VN) of C32 human melanoma cells which express IAP, alpha v beta 3, and alpha v beta 5. Cells adhere to VN at low surface densities via alpha v beta 5 and spread very slowly while adhesion to higher density VN involves both alpha v beta 5 and alpha v beta 3 and results in rapid spreading. Spreading of the cells, but not adhesion, on sparse VN coatings is markedly enhanced by the presence of soluble TS1, the recombinant CBD and 4N1K, but not the "mutant" peptide 4NGG, KRFYGGMWKK, which fails to bind IAP. This enhanced spreading is completely blocked by mAb LM609 against alpha v beta 3 and the anti-IAP mAb B6H12. Correlated with this enhanced spreading is increased tyrosine phosphorylation of focal adhesion kinase (FAK), paxillin, and a protein of ca. 90 kD. The enhanced spreading induced by TS1 and 4N1K and the constitutive spreading on higher density VN are both blocked by calphostin C (100 nM), wortmannin (10 nM), and tyrosine kinase inhibitors. In contrast, pertussis toxin specifically blocks only the TS1 stimulated spreading on low density VN, indicating that IAP exerts its effects on signal transduction via a heterotrimeric Gi protein acting upstream of a common cell spreading pathway which includes PI-3 kinase, PKC, and tyrosine kinases.

Стилі APA, Harvard, Vancouver, ISO та ін.

Kulhandjian, Michel, Hovannes Kulhandjian, Claude D'amours, and Lajos Hanzo. "Low-Density Spreading Codes for NOMA Systems and a Gaussian Separability-Based Design." IEEE Access 9 (2021): 33963–93. http://dx.doi.org/10.1109/access.2021.3060879.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Yoshikuni, Masato, Shinji Ide, Nobuyuki Iwata, and Hiroshi Yamamoto. "Field Emission from Low Density Carbon Nanofiber Emitters Prepared by Spray Spreading Method." Molecular Crystals and Liquid Crystals 472, no. 1 (August 20, 2007): 87/[477]—94/[484]. http://dx.doi.org/10.1080/15421400701545155.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Foster, Natalie D., Andrew J. Miller, Troy A. Hutchins-Delgado, Christopher M. Smyth, Michael C. Wanke, Tzu-Ming Lu, and Dwight R. Luhman. "Thermal activation of low-density Ga implanted in Ge." Applied Physics Letters 120, no. 20 (May 16, 2022): 201902. http://dx.doi.org/10.1063/5.0094900.

Повний текст джерела

Анотація:

The nuclear spins of low-density implanted Ga atoms in Ge are interesting candidates for solid state-based qubits. To date, activation studies of implanted Ga in Ge have focused on high densities. Here, we extend activation studies into the low-density regime. We use spreading resistance profiling and secondary ion mass spectrometry to derive electrical activation of Ga ions implanted into Ge as a function of the rapid thermal anneal temperature and implant density. We show that for our implant conditions, the activation is best for anneal temperatures between 400 and 650 °C with a maximum activation of 69% at the highest fluence. Below 400 °C, remaining implant damage results in defects that act as superfluous carriers, and above 650 °C, surface roughening and loss of Ga ions are observed. The activation increased monotonically from 10% to 69% as the implant fluence increased from [Formula: see text] to [Formula: see text] cm−2. The results provide thermal anneal conditions to be used for initial studies of using low-density Ga atoms in Ge as nuclear spin qubits.

Стилі APA, Harvard, Vancouver, ISO та ін.

Більше джерел

Дисертації з теми "Low Density Spreading"

Fantuz, Mitchell. "Multi-User Detection of Overloaded Systems with Low-Density Spreading." Thesis, Université d'Ottawa / University of Ottawa, 2019. http://hdl.handle.net/10393/39600.

Повний текст джерела

Анотація:

Future wireless networks will have applications that require many devices to be connected to the network. Non-orthogonal multiple access (NOMA) is a promising multiple access scheme that allows more users to simultaneously transmit in a common channel than orthogonal signaling techniques. This overloading allows for high spectral efficiencies which can support the high demand for wireless access. One notable NOMA scheme is low-density spreading (LDS), which is a code domain multiple access scheme. Low density spreading operates like code division multiple access (CDMA) in the sense that users use a spreading sequence to spread their data, but the spreading sequences have a low number of nonzero chips, hence the term low-density. The message passing algorithm (MPA) is typically used for multi-user detection (MUD) of LDS systems. The MPA detector has complexity that is exponential to the number of users contributing to each chip. LDS systems suffer from two inherent problems: high computational complexity, and vulnerability to multipath channels. In this thesis, these two problems are addressed. A lower complexity MUD technique is presented, which offers complexity that is proportional to the number of users squared. The proposed detector is based on minimum mean square error (MMSE) and parallel interference cancellation (PIC) detectors. Simulation results show the proposed MUD technique achieves reductions in multiplications and additions by 81.84% and 67.87% with a loss of about 0.25 dB with overloading at 150%. In addition, a precoding scheme designed to mitigate the effects of the multipath channel is also presented. This precoding scheme applies an inverse channel response to the input signal before transmission. This allows for the received signal to eliminate the multipath effects that destroy the low-density structure.

Стилі APA, Harvard, Vancouver, ISO та ін.

DHAKAL, PAWAN. "Algorithms for 5G physical layer." Doctoral thesis, Politecnico di Torino, 2017. http://hdl.handle.net/11583/2670627.

Повний текст джерела

Анотація:

There is a great activity in the research community towards the investigations of the various aspects of 5G at different protocol layers and parts of the network. Among all, physical layer design plays a very important role to satisfy high demands in terms of data rates, latency, reliability and number of connected devices for 5G deployment. This thesis addresses he latest developments in the physical layer algorithms regarding the channel coding, signal detection, frame synchronization and multiple access technique in the light of 5G use cases. These developments are governed by the requirements of the different use case scenarios that are envisioned to be the driving force in 5G. All chapters from chapter 2 to 5 are developed around the need of physical layer algorithms dedicated to 5G use cases. In brief, this thesis focuses on design, analysis, simulation and he advancement of physical layer aspects such as 1. Reliability based decoding of short length Linear Block Codes (LBCs) with very good properties in terms of minimum hamming istance for very small latency requiring applications. In this context, we enlarge the grid of possible candidates by considering, in particular, short length LBCs (especially extended CH codes) with soft-decision decoding; 2. Efficient synchronization of preamble/postamble in a short bursty frame using modified Massey correlator; 3. Detection of Primary User activity using semiblind spectrum sensing algorithms and analysis of such algorithms under practical imperfections; 4. Design of optimal spreading matrix for a Low Density Spreading (LDS) technique in the context of non-orthogonal multiple access. In such spreading matrix, small number of elements in a spreading sequences are non zero allowing each user to spread its data over small number of chips (tones), thus simplifying the decoding procedure using Message Passing Algorithm (MPA).

Стилі APA, Harvard, Vancouver, ISO та ін.

Hong, Pei-hao, and 洪培皓. "Minimum BER Orthogonal Low-density Spreading Code for Spreading OFDM Systems." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/38601056590427461165.

Повний текст джерела

Анотація:

碩士
國立臺灣科技大學
電子工程系
103
The thesis proposes the minimum BER orthogonal low-density spreading code for spreading OFDM system. We first derive the sufficient condition for minimizing BER. The sufficient condition is to minimize the probability that any two codewords has the number of different elements equals to the spreading factor. Therefore, we next propose two low-density codes which may minimize this probability. The first low-density code constructed by concatenating a rotated phase matrix, low-density Hadamard matrices and permutation matrices offers the near-minimum probability. With the near-minimum probability, the first low-density code offers the near-minimum BER. The second low-density constructed by the brute-force search offers the minimum probability. With the minimum probability, the second low-density code offers the minimum BER. Simulations show low-density codes we propose significantly improves the BER of the other conventional high-density codes. The improvement can be over 3 dB for high order modulation. In particular, the BER of the second low-density reaches the match filter bound in the high SNR region.

Стилі APA, Harvard, Vancouver, ISO та ін.

Vlok, Jacobus David. "Sparse graph codes on a multi-dimensional WCDMA platform." Diss., 2007. http://upetd.up.ac.za/thesis/available/etd-07042007-155428.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Частини книг з теми "Low Density Spreading"

Al-Imari, Mohammed, and Muhammad Ali Imran. "Low Density Spreading Multiple Access." In Multiple Access Techniques for 5G Wireless Networks and Beyond, 493–514. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-92090-0_15.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Phethean, Jordan J. J., Martha Papadopoulou, and Alexander L. Peace. "Dense melt residues drive mid-ocean-ridge “hotspots”." In In the Footsteps of Warren B. Hamilton: New Ideas in Earth Science. Geological Society of America, 2022. http://dx.doi.org/10.1130/2021.2553(30).

Повний текст джерела

Анотація:

ABSTRACT The geodynamic origin of melting anomalies found at the surface, often referred to as “hotspots,” is classically attributed to a mantle plume process. The distribution of hotspots along mid-ocean-ridge spreading systems around the globe, however, questions the universal validity of this concept. Here, the preferential association of hotspots with slow- to intermediate-spreading centers and not fast-spreading centers, an observation contrary to the expected effect of ridge suction forces on upwelling mantle plumes, is explained by a new mechanism for producing melting anomalies at shallow (<2.3 GPa) depths. By combining the effects of both chemical and thermal density changes during partial melting of the mantle (using appropriate latent heat and depth-dependent thermal expansivity parameters), we find that mantle residues experience an overall instantaneous increase in density when melting occurs at <2.3 GPa. This controversial finding is due to thermal contraction of material during melting, which outweighs the chemical buoyancy due to melting at shallow pressures (where thermal expansivities are highest). These dense mantle residues are likely to locally sink beneath spreading centers if ridge suction forces are modest, thus driving an increase in the flow of fertile mantle through the melting window and increasing magmatic production. This leads us to question our understanding of sub–spreading center dynamics, where we now suggest a portion of locally inverted mantle flow results in hotspots. Such inverted flow presents an alternative mechanism to upwelling hot mantle plumes for the generation of excess melt at near-ridge hotspots, i.e., dense downwelling of mantle residue locally increasing the flow of fertile mantle through the melting window. Near-ridge hotspots, therefore, may not require the elevated temperatures commonly invoked to account for excess melting. The proposed mechanism also satisfies counterintuitive observations of ridge-bound hotspots at slow- to intermediate-spreading centers, yet not at fast-spreading centers, where large dynamic ridge suction forces likely overwhelm density-driven downwelling. The lack of observations of such downwelling in numerical modeling studies to date reflects the generally high chemical depletion buoyancy and/or low thermal expansivity parameter values employed in simulations, which we find to be unrepresentative for melting at <2.3 GPa. We therefore invite future studies to review the values used for parameters affecting density changes during melting (e.g., depletion buoyancy, latent heat of melting, specific heat capacity, thermal expansivity), which quite literally have the potential to turn our understanding of mantle dynamics upside down.

Стилі APA, Harvard, Vancouver, ISO та ін.

Sarkar, Bidisa, and Kamalesh Sarkar. "Control of an Epidemic of SARS-CoV-2 by Assessing Transmissibility of Its Infected Cases in Absence of a Suitable Vaccine." In Biotechnology to Combat COVID-19 [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.96201.

Повний текст джерела

Анотація:

SARS-CoV-2 or Covid 19 and it’s pandemicity has been wreaking havoc in many countries worldwide. It is important to counter and contain the spread of Covid-19 using some effective infection control policies as we await an effective protection such as vaccine. Ahmedabad Model of Covid-19 Control could be used as an established epidemic management protocol due to COVID 19 infection. It relies on the Cycle Threshold (Ct) Value, which was used as a proxy marker for assessing initial viral load. It was evident that cases with higher viral load spread the disease at much higher rate compared to that of low viral load apart from population mobility and/or population density. Therefore, Ct value based segregation of infected cases with higher viral load along with contact tracing of them of previous 5 days is an effective epidemic control policy. It needs to be remembered that a section of infected cases is asymptomatic and capable of spreading infection in the community unknowingly. Hence, infection control practices must be accompanied with standard precautionary measures such as physical distancing, hand hygiene and wearing face mask. Community awareness is an integral part of it. Newer biotechnology based researches may be encouraged based on felt needs.

Стилі APA, Harvard, Vancouver, ISO та ін.

Тези доповідей конференцій з теми "Low Density Spreading"

AL-Imari, Mohammed, Muhammad Ali Imran, Rahim Tafazolli, and Dageng Chen. "Performance evaluation of Low Density Spreading Multiple Access." In 2012 8th International Wireless Communications and Mobile Computing Conference (IWCMC 2012). IEEE, 2012. http://dx.doi.org/10.1109/iwcmc.2012.6314235.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

AL-Imari, Mohammed, Muhammad Ali Imran, and Rahim Tafazolli. "Low Density Spreading for next generation multicarrier cellular systems." In 2012 International Conference on Future Communication Networks (ICFCN). IEEE, 2012. http://dx.doi.org/10.1109/icfcn.2012.6206872.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Asgharimoghaddam, Hossein, and Antti Tolli. "Resource Allocation in Low Density Spreading Uplink NOMA via Asymptotic Analysis." In 2020 IEEE International Symposium on Information Theory (ISIT). IEEE, 2020. http://dx.doi.org/10.1109/isit44484.2020.9174401.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Zhang, Jian, Xin Wang, Xianjun Yang, and Hua Zhou. "Low Density Spreading Signature Vector Extension (LDS-SVE) for Uplink Multiple Access." In 2017 IEEE 86th Vehicular Technology Conference (VTC-Fall). IEEE, 2017. http://dx.doi.org/10.1109/vtcfall.2017.8287908.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Cheung, Chun, and Roger S. Cheng. "Adaptive Modulation in Frequency Spreading OFDM System with Low Transmit Power Spectral Density Constraint." In 2007 IEEE Wireless Communications and Networking Conference. IEEE, 2007. http://dx.doi.org/10.1109/wcnc.2007.270.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Miao, Guanxiong, Wenchao Du, Zhijian Pei, and Chao Ma. "Binder Jetting Additive Manufacturing of Ceramics: Analytical and Numerical Models for Powder Spreading Process." In ASME 2019 14th International Manufacturing Science and Engineering Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/msec2019-2925.

Повний текст джерела

Анотація:

Abstract Binder jetting additive manufacturing is a promising way to process ceramic materials which are hard to be manufactured into complex shapes using conventional methods. However, the application of binder jetting is limited by the relatively low density of manufactured parts. Powder bed forming process is a critical step that determines the powder bed density and consequently the part density. Thus, investigating and understanding the power spreading process is necessary to improve the part density. A numerical model is developed to predict the powder bed density under different spreading conditions using the discrete element method (DEM). The predicted DEM results are compared with the prediction of an analytical model. The results show that under different layer thicknesses (50 μm, 70 μm, 100 μm) and roller diameters (12 mm, 14 mm, and 16 mm), the predicted maximum powder bed density by these two models has nearly the same value and the predicted maximum packing stress has the same trend.

Стилі APA, Harvard, Vancouver, ISO та ін.

Nowicki, Natalie L. "Effects of Density on Mixing of Low Reynolds Number Vertical Jets." In ASME 2006 International Mechanical Engineering Congress and Exposition. ASMEDC, 2006. http://dx.doi.org/10.1115/imece2006-16353.

Повний текст джерела

Анотація:

Laser sheet smoke visualization experiments were performed on vertical air/helium jets to quantify the effects of low density driven bursts on the jet structure and entrainment. The parameters of relative jet density, S, and jet exit Reynolds number, Re, are of most importance in determining the bursting. Previous research has shown that vertical jets of S ≤ 0.5, in a range of Rej = 1300 – 2500, display strong side ejections due to the baroclinic instability in the strained vorticity sheet between the primary torroidal vortices. The objective of this work was to determine if this phenomenon resulted in a significant increase in the mixing and jet entrainment compared to standard jets. The present study demonstrated that the strong and clearly visible burst phenomenon had a very minor impact on the time averaged spreading and mixing in the shear layer surrounding the potential core. Experiments were performed using laser sheet illumination with a YAG pulse laser and cylindrical lens with oil smoke droplet seeding. The images were acquired using a 12 bit CCD camera with a 1024 × 1280 pixel array. All images were acquired at a low enough frequency to ensure their statistical independence. The laser sheet was estimated to be 0.5 mm thick with a pulse duration of 6 ns. Planar instantaneous images both coplanar and normal to the jet centerline were obtained. The jet emerged into room air from an 11 mm diameter bicubic nozzle with a contraction ratio of 5.5. Mixed flows of air and helium were fed into a settling chamber and then passed through a flow straightening honeycomb upstream of the jet. Flow rates and Reynolds numbers were controlled using choked flow nozzles that fed the settling chamber. Oil droplet smoke was added to the air flow with an adiabatic venturi-jet oil atomizer. In the instantaneous images of the jets, the bursts were clearly visible in individual frames and qualitatively appeared to play a significant role in the downstream mixing of the jet. However, quantitative analysis of time averages of many sequential images revealed that the bursts are much less significant to the mixing and entrainment of the jet than they appear. Longitudinal images were acquired in sets of 100 or 200 and used to obtain averaged images of the plume from the source out to approximately 10 jet diameters. The pixel noise floor was subtracted from the mean images. These mean images were interpreted as an analogue for scalar concentration, and thus used to quantitatively estimate the plume spread. From these mean images, concentration profiles were obtained and plotted. The bursting phenomenon was shown to be insignificant on an engineering scale after analyzing the mean images. In fact, the mass in the region where the bursts occurred was only visible when a function which showed very small gradient differences was applied to the images. While the baroclinic instability bursting is interesting from a scientific point of view, it has been shown through the quantitative analysis of the means of instantaneous images that there is only a slight effect on the overall jet entrainment compared with regular jets.

Стилі APA, Harvard, Vancouver, ISO та ін.

Gupta, Amit, and Ranganathan Kumar. "Simulation of Droplet Flows Using Lattice Boltzmann Method." In ASME 2008 6th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2008. http://dx.doi.org/10.1115/icnmm2008-62372.

Повний текст джерела

Анотація:

In this work, the mesoscale approach of two-dimensional lattice Boltzmann method (LBM) has been employed to study droplet collision with a dry wall. The impact of drops with solid walls is simulated by using the pseudo-potential method of LBM. Simulations have been conducted for 2<We<162, and it is shown that the maximum spreading of the drop on the solid surface depends on the surrounding density, velocity of impact, surface tension, and the surface wetting characteristics. For a short time interval right after the impact the spreading diameter is shown to follow a parabolic dependence with time. The spread factor is seen to be higher as the Weber number increases. Under certain conditions when the drop has a high impact velocity and/or low surface tension, the kinetic energy of impact dominates over the dissipation and surface energy, leading to breakup of the drop into smaller drops. This breakup is shown to depend upon the wetting/non-wetting nature of the surface used. The spread factor is found to be a maximum at the time of breakup.

Стилі APA, Harvard, Vancouver, ISO та ін.

Aleyasin, Seyed Sobhan, and Mark Francis Tachie. "Comparative Evaluation of Single/Twin Round and Elliptic Jets Using Particle Image Velocimetry." In ASME 2018 5th Joint US-European Fluids Engineering Division Summer Meeting. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/fedsm2018-83495.

Повний текст джерела

Анотація:

Twin round and elliptic jets with nozzle spacing of S/d = 2.8 are investigated and the results are compared with those obtained from single jets. The measurements were performed at Re = 10000 using particle image velocimetry. The results show that the twin elliptic jets merge and combine faster than the round jets. However, the twin elliptic jets have lower spreading than their corresponding single jet but in the round jets it is opposite. The vortical structures obtained using swirling strength analysis are more intense in the elliptic jets compared with the round jets; consistent with their higher spreading. In the shear layers, the velocity skewness is considerably positive due to the diffusion of high-speed jet fluid towards the ambient. On the other hand, the streamwise skewness on the centerline is negative because of the entrainment of low-speed ambient fluid; resulting in centerline velocity decay. In addition, the joint and weighted joint probability density functions are used to understand the dominant events which contribute into the mixing of the jets with their surrounding fluid.

Стилі APA, Harvard, Vancouver, ISO та ін.

Altman, David H., Anurag Gupta, Thomas E. Dubrowski, Darin J. Sharar, Nicholas R. Jankowski, and Mark T. North. "Analysis and Characterization of Thermal Expansion-Matched Wick-Based Multi-Chip Passive Heat Spreaders in Static and Dynamic Environments." In ASME 2013 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/ipack2013-73087.

Повний текст джерела

Анотація:

Ensuring adequate spreading of heat dissipated by high power density devices is a critical part of many electronics packaging designs. In many cases, passive wick-based heat spreaders can offer improved heat spreading performance relative to solid conductor alternatives. However, concerns related to performance degradation in high-inertial force environments frequently limit their use to static or near-static applications. In this work we investigate the performance of low coefficient of thermal expansion (CTE) wick-based heat spreaders cooling multiple high heat flux devices in static and high-g environments. Two high-power devices are simulated using custom-manufactured resistor-thermometer chips, enabling dissipation of die average heat fluxes in excess of 150W/cm2. Comparative thermal performance is evaluated for wick-based heat spreaders and solid CuMo heat spreaders of equivalent CTE affixed with interface materials typical of those used when attaching a low CTE package to a high CTE cold plate (e.g., Al or Cu). Thermal performance is characterized as a function of heat input during exposure to increasing g-forces applied using a custom-built centrifuge. Experimental observations are interpreted through detailed modeling of fluid flow patterns within the wick structure of the passive heat spreader. Results from these experiments demonstrate that properly designed wick-based heat spreaders have utility in both static and dynamic environments, exhibiting effective conductivities in excess of that obtainable with competitive low-expansion composites.

Стилі APA, Harvard, Vancouver, ISO та ін.

Ми пропонуємо знижки на всі преміум-плани для авторів, чиї праці увійшли до тематичних добірок літератури. Зв'яжіться з нами, щоб отримати унікальний промокод!