Results 11 - 20 of 5158
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[en] During the Pyrenees Experiment (PYREX) in October and November 1990 in radiosonde network was in operation with enhanced spatial and temporal resolution. This atlas contains standardized output from a three-dimensional, objective analysis scheme which is used to interpolate from the observed significant levels to a regular grid centred over the Pyrenees. For each of the 68 release times during ten intensive observation periods 12 horizontal charts are displayed on one page. These charts contain temperature, relative humidity or potential vorticity, and horizontal wind (vectors and isotachs) in four levels. The atlas is considered as basic material for more detailed studies at or between selected release times. (orig.)
[de]Waehrend des Pyrenaeen Experiments (PYREX) wurde im Oktober und November 1990 ein Radiosondennetz mit erhoehter raeumlicher und zeitlicher Aufloesung betrieben. Dieser Atlas enthaelt standardisierte Ergebnisse eines drei-dimensionalen, objektiven Analysenschemas, mit dessen Hilfe von den Beobachtungen an allen signifikanten Punkten auf ein regulaeres, ueber den Pyrenaeen zentriertes Gitter interpoliert wurde. Fuer jeden der 68 Aufstiegstermine innerhalb der zehn intensiven Beobachtungsphasen sind 12 horizontale Karten auf einer Seite zusammengefasst. Diese enthalten Temperatur, relative Feuchte oder potentielle Vorticity, sowie den Horizontalwind (Vektoren und Isotachen) in vier Niveaus. Der Atlas stellt Grundlagenmaterial bereit fuer eingehendere Studien zu oder zwischen einzelnen Aufstiegsterminen. (orig.)
[en] Pressure agglomeration of powders is widely applied in various industries and an increasing interest lies in the identification and description of contact mechanisms between particles, which are responsible for the compaction product properties. In this paper, the design and development of a novel micromanipulation particle tester (MPT) is presented. This device makes it possible to measure the deformation kinetics and resulting adhesion of two individual particles in contact under load, which are strongly influenced by the applied process conditions. The MPT set-up is, therefore, designed to offer a unique control over the process conditions most relevant to the compaction of powders: external stress, dwell or holding time at constant deformation, compression velocity as well as relative humidity and temperature determining the physical state and mechanical characteristics of hygrosensitive amorphous particles. The latter are often part of powder formulations, e.g. in the food industry, and have been used for force and contact-zone development studies with the MPT. The experimental results on the microscale level will deliver valuable quantitative information for an improved tailoring of pressure agglomeration process conditions of bulk solids. (paper)
[en] During the electro spinning process the web of nano fibres is manufactured by means of electrostatic forces between two electrodes. The diameters of nano fibres usually differ and they depend on various parameters. The different fineness of fibres influences the structure of the web and herewith the end-use properties of such kind of nano material. Analysis of nano fibres diameters distribution also shows big differences; even more, the distributions are not spread along the normal distribution. Understanding the influence of electro spinning parameters and the reason why the shapes of distributions are so sophisticated is very important. The goal of this paper is to analyse the distribution of diameter and to propose the new criterion for nano fibres diameter comparison and web of nano fibres estimation. In this paper the influence of covering time of support material on structure of PA6.6 nano fibre web has been investigated. It was estimated that this parameter does not have a significant influence on the average diameter of nano fibres, and only the structure of web has been influenced by the changes in covering time. According to the results provided the phenomena of nano fibres sticking on the support material at the time of electro spinning can be proved and explained.
[en] A ground-based field campaign was conducted during the summer of 2011, 10 km east of the Israeli coast, aimed at studying small, warm convective clouds. During the campaign, clouds were detected on days that were predicted to be cloud-free by standard forecasting methods. Moreover, the clouds’ bases were often much lower than the estimated lifting condensation level. Detailed air parcel model simulations revealed that such small non-buoyant clouds can form only if the convective motion is driven by perturbations in the relative humidity in the middle of the boundary layer, rather than by temperature perturbations near the surface. Furthermore, cloud base height exhibited weak sensitivity to the initial elevation of the parcel, suggesting that it serves as an accumulation point for many relative-humidity-perturbed thermodynamic trajectories. Such a mechanism is likely to be common under atmospheric conditions of a hot and humid boundary layer capped by a strong inversion layer. (letter)
[en] The data centre at the Galician Institute of High Energy Physics (IGFAE) of the Santiago de Compostela University (USC) is a computing cluster with about 150 nodes and 1250 cores that hosts the LHCb Tiers 2 and 3. In this small data centre, and of course in similar or bigger ones, it is very important to keep optimal conditions of temperature, humidity and pressure. Therefore, it is a necessity to monitor the environment and be able to trigger alarms when operating outside the recommended settings. There are currently many tools and systems developed for data centre monitoring, but until recent years all of them were of commercial nature and expensive. In recent years there has been an increasing interest in the use of technologies based on Arduino due to its open hardware licensing and the low cost of this type of components. In this article we describe the system developed to monitor IGFAE's data centre, which integrates an Arduino controlled sensor network with the Nagios monitoring software. Sensors of several types, temperature, humidity and pressure, are connected to the Arduino board. The Nagios software is in charge of monitoring the various sensors and, with the help of Nagiosgraph, to keep track of the historic data and to produce the plots. An Arduino program, developed in house, provides the Nagios plugin with the readout of one or several sensors depending on the plugin's request. The Nagios plugin for reading the temperature sensors also broadcasts an SNMP trap when the temperature gets out of the allowed operating range.
[en] Highlights: • Triboelectric nanogenerator was prepared using force-assembled colloidal arrays. • The electrical performance was determined by the structures and colloidal size. • They displayed high electric output, stability, and humidity resistance. We introduce a novel, robust, cost-effective, and scalable approach for the preparation of a large-area force-assembled triboelectric nanogenerator (FTENG), which allows a stable and high electric output under a wide range of humidity conditions through its dual-sized morphology (i.e., microstructures and nanostructures). In this study, hexagonally packed colloidal arrays prepared by a force assembly approach rather than by conventional self-assembly were used as a mold for a triboelectric poly(dimethylsiloxane) (PDMS) replica with desired pattern shapes (intaglio and embossed structures) and sizes. The morphological size of the PDMS films was determined by the diameter of the force-assembled colloids. The electrical output performance of FTENGs composed of electrodes and a PDMS film increased substantially as the size of the micropores (for intaglio-structured PDMS) or embossed features (for embossed-structured PDMS) decreased. Furthermore, the triboelectric PDMS film with micro-/nanosized features (i.e., dual-embossed PDMS) displayed a remarkable electrical output of 207 V (open-circuit voltage under a compressive force of 90 N in relative humidity (RH) of 20%) and high hydrophobicity compared to that of PDMS films with flat, intaglio or embossed structures. This device maintained a high electric output even in a high-humidity environment (i.e., open-circuit output voltage ~175 V in RH 80%). Our approach using force-assembly and hierarchical surface morphology will provide a novel and effective framework for developing strong power sources in various self-powered electronics.
[en] The results of a research carried out in order to improve sustainability in the University of Informatics Sciences in Havana are presented in the paper. The initial qualitative evaluation of the three more energy consumer buildings allow to identify main problems and to select indoor spaces where temperature and relative humidity were measured. Intervention proposals were elaborated which positive impact was verified by automatized simulation of results and its comparison to the departing situation. The results of the empirical research corroborate the integral qualitative evaluation carries out. It has been demonstrated that it is possible to reduce indoor temperature by modifying the envelope without high investments, if advantage is taken from benefit of green shadow. (author)
[en] A common coldrex, paracetamol, was used as humidity sensing material. The capacitance-type humidity sensor was fabricated by aerosol deposition method. The humidity sensitive properties were investigated through dielectric measurements. Our results reveal that the sensor has exciting performances in high relative humidity. Both −OH and −NH groups have contributions to water absorption. The −OH groups lead to a water-containing surface layer giving rise to pronounced Maxwell-Wagner response, which in turn, yields the humidity response that can be easily adjusted by an external electric field. This work indicates that the paracetamol is a promising humidity sensing material. (paper)
[en] The accuracy of the quantitative sensing of volatile organic compounds by chemoresistive gas sensors suffers from the fluctuations in the background atmospheric conditions. This is caused by the drift-like terms introduced in the responses by these instabilities, which should be identified and compensated. Here, a mathematical model is presented for a specific chemoresistive gas sensor, which facilitates these identification and compensation processes. The resistive gas sensor was considered as a multi-input-single-output system. Along with the steady state value of the measured sensor resistance, the ambient humidity and temperature are the inputs to the system, while the concentration level of the target gas is the output. The parameters of the model were calculated based on the experimental database. The model was simulated by the utilization of an artificial neural network. This was connected to the sensor and could deliver the correct contamination level upon receiving the measured gas response, ambient humidity and temperature.