354 research outputs found
Optimal design of experiments with simulation models of nearly saturated queues
No full textexperimental design;simulation models;queueing network;regression analysis
Voice Compression and Communications: Principles and Applications for Fixes and Wireless Channels
No full textUp-to-date, expert coverage of topics in wireless voice communications Voice communication is the most important facet of mobile radio service. Even when the predicted surge of wireless data and Internet services becomes a reality, voice will remain the most natural means of human communication. Voice Compression and Communications details issues in wireless voice communications and treats compression, channel coding, and wireless transmission as a joint subject. Part I covers background material, whereas Part II provides detailed information on both proprietary and standardized analysis-by-synthesis codecs, including the speech codecs of virtually all existing wireline-based and wireless systems. Parts III and IV discuss mainly research-based wideband, audio, as well as very low-rate schemes likely to find their way into future standards. Voice Compression and Communications describes fundamental concepts in a non-mathematical way early in the book for those with only a background knowledge of signal processing and communications. More advanced readers will find detailed discussions of theoretical principles, future concepts, and solutions to various specific wireless voice communications problems
LOUDNESS OF SOUNDS OF DIFFERENT FREQUENCY AND INTENSITY: THE GENERALIZED WEBER LAW FOR HEARING
No full textAim - rigorous scientificand theoretical substantiation of the Weber law for determination of loudness of sounds of different frequency and intensity. Objects and methods. E.H. Weber's experimental results on subjective perception of objectively measured parameters of external irritants, their theoretical substantiation for sounds of the standard frequency 1 kHz, biophysical and biomathematical modeling of loudness of sounds with different parameters. Results. The Weber law by author for determination of loudness of sounds of different frequency and intensity is evidence based
A universal metric for ferroic energy materials
No full textAfter almost 20 years of intensive research on magnetocaloric effects near room temperature, magnetic refrigeration with first-order magnetocaloric materials has come close to real-life applications. Many materials have been discussed as potential candidates to be used in multicaloric devices. However, phase transitions in ferroic materials are often hysteretic and a metric is needed to estimate the detrimental effects of this hysteresis. We propose the coefficient of refrigerant performance, which compares the net work in a reversible cycle with the positive work on the refrigerant, as a universal metric for ferroic materials. Here, we concentrate on examples from magnetocaloric materials and only consider one barocaloric experiment. This is mainly due to lack of data on electrocaloric materials. It appears that adjusting the field-induced transitions and the hysteresis effects can minimize the losses in first-order materials. This article is part of the themed issue 'Taking the temperature of phase transitions in cool materials'.</p
Magnetic-Anisotropy in UTX Compounds
No full textHavela, L.; Sechovsky, V.; Nakotte, H.; Bruck, E.H. General rights It is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulations If you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: https://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible
Seasonal COP of a residential magnetocaloric heat pump based on MnFePSi
No full textThe performance of a magnetocaloric heat pump (MCHP) consisting of active magnetocaloric regenerators (AMR) of 12 layers of MnFePSi magnetocaloric materials (MCM) with a linear distribution of Curie temperatures was investigated using a 1D numerical model. The model predicted the heating power and coefficient of performance (COP) of the AMR for a fixed temperature span of 27 K, between 281 K and 308 K, and variable flow rate and AMR cycle frequency. A maximum applied magnetic field strength of 1.4 T was used. A well-insulated house with a maximum heating power demand of 3 kW (under quasi steady state conditions) was considered. Ambient temperature in The Netherlands was taken as a reference for the estimation of the seasonal heating power demand. Without optimizing the design of the AMR, the model predicts a maximum single-AMR heating power equal to 43.5 W when the AMR operates at 3 Hz and 3 L min-1, and a maximum COP equal to 5.8 when it operates at 1.5 Hz and 1 L min-1 Considering the maximum heating power of a single AMR, approximately 69 AMRs are needed to provide the design heating power demand of the house. It was found that it is possible to achieve an AMR seasonal COP of 5.6 by continuously adjusting the flow rate and frequency of operation of the MCHP along with the ON/OFF switching of some groups of AMRs in order to adjust the heating power of the MCHP to the heating power demand of the house.RST/Fundamental Aspects of Materials and EnergyEngineering ThermodynamicsRST/Radiation, Science and Technolog
Acid Sphingomyelinase Deficiency Type B Patient-Derived Liver Organoids Reveals Altered Lysosomal Gene Expression and Lipid Homeostasis
No full textAuthor Contributions: Conceptualization, G.G.-M. and S.P.-L.; methodology, G.G.-M., S.P.-L., S.R.-D.S., E.H.-S., M.F.-P. and N.M.; validation, S.P.-L., S.R.-D.S., E.H.-S., M.F.-P. and N.M.; formal analysis, G.G.-M., S.P.-L. and S.G.-M.; resources, I.J. and A.M.; writing—original draft preparation, G.G.-M. and S.P.-L.; writing—review and editing, S.P.-L., B.M.-D. and N.M.; supervision, B.M.-D.; funding acquisition, B.M.-D. All authors have read and agreed to the published version of the manuscript.Acid sphingomyelinase deficiency (ASMD) or Niemann–Pick disease type A (NPA), type B (NPB) and type A/B (NPA/B), is a rare lysosomal storage disease characterized by progressive accumulation of sphingomyelin (SM) in the liver, lungs, bone marrow and, in severe cases, neurons. A disease model was established by generating liver organoids from a NPB patient carrying the p.Arg610del variant in the SMPD1 gene. Liver organoids were characterized by transcriptomic and lipidomic analysis. We observed altered lipid homeostasis in the patient-derived organoids showing the predictable increase in sphingomyelin (SM), together with cholesterol esters (CE) and triacylglycerides (TAG), and a reduction in phosphatidylcholine (PC) and cardiolipins (CL). Analysis of lysosomal gene expression pointed to 24 downregulated genes, including SMPD1, and 26 upregulated genes that reflect the lysosomal stress typical of the disease. Altered genes revealed reduced expression of enzymes that could be involved in the accumulation in the hepatocytes of sphyngoglycolipids and glycoproteins, as well as upregulated genes coding for different glycosidases and cathepsins. Lipidic and transcriptome changes support the use of hepatic organoids as ideal models for ASMD investigation.Instituto de Salud Carlos IIISección Deptal. de Bioquímica y Biología Molecular (Veterinaria)Fac. de VeterinariaTRUEpu
In Memoriam Professor Dr.-Ing. Dr.-Ing. E.h. Wolfgang Straßer (10.08.1941-24.01.2015)
No full textS.165-166Wolfgang Straßer was a longtime supporter of the Computers and Graphics Journal, where he was a member of the Editorial Board since the early 1990s. His contributions to this Journal as an Author, Reviewer and Adviser were numerous and relevant. Joaquim Jorge still remembers fondly meeting Wolfgang Straßer in the early days of the Graphics Hardware Workshop. In more recent years, his suggestions, contributions and comments were helpful in shaping the editorial line of Computers and Graphics.4
Effect of goethite doping using elements with different preferential oxidation states for improved reversible phosphate adsorption
No full textPhosphorus (P) removal from freshwater bodies to ultra-low concentrations is fundamental to prevent eutrophication, while its recovery is necessary to close the P usage cycle. Iron oxide-based adsorbents seem promising candidates, being abundant, cheap, and easy to synthesize compounds, with good affinity for P. Affinity is the key parameter when targeting ultra-low concentrations. Also, adsorbent regeneration and re-use is fundamental for the economic viability, hence the adsorbent stability is important. Goethite, (α-FeOOH), is one of the most stable iron (Fe3+) (hydr)oxide species, with higher affinity, but lower adsorption capacity (per kg) compared to other species. Doping could change goethite surface properties, to boost the adsorption capacity, while preserving the high stability and affinity for P. In this work, pure goethite was compared to goethite doped (5%at.) with different elements of different preferential oxidation states: Zn2+, Mn3+, and Zr4+. Doping was successfully achieved for all elements, albeit Zr showed a lower Fe substitution than targeted. Zn doping increased the goethite point of zero charge and adsorption capacity (per mass and per surface area), preserving the high affinity, while Mn- and Zr- doping displayed a decrease in all the parameters. These could be explained with surface protonation as a charge compensation mechanism in Zn2+-for-Fe3+ substitution. The regeneration test showed improved P recovery for Zr- and Zn-doped goethite. All samples remained stable throughout the whole process. This work provides promising insights on doping as a strategy to manipulate iron oxides surface properties and for developing a highly performing and long-lasting goethite-based adsorbent.RST/Fundamental Aspects of Materials and EnergyBT/Environmental BiotechnologyRID/TS/Instrumenten groe
In Memoriam Professor Dr.-Ing. Dr.-Ing. E.h. Wolfgang Straßer (10.08.1941-24.01.2015)
No full textWolfgang Straßer was a longtime supporter of the Computers and Graphics Journal, where he was a member of the Editorial Board since the early 1990s. His contributions to this Journal as an Author, Reviewer and Adviser were numerous and relevant. Joa- quim Jorge still remembers fondly meeting Wolfgang Straßer in the early days of the Graphics Hardware Workshop. In more recent years, his suggestions, contributions and comments were helpful in shaping the editorial line of Computers and Graphics
- …
