2,057 research outputs found
Experimental study on a solar-powered thermochemical sorption refrigeration system using strontium chloride/EG-ammonia working pair
An experimental intermittent thermochemical refrigeration system using strontium chloride (SrCl2)–ammonia reaction is described, which mainly consists of an adsorption bed and an evaporator/condenser. The strontium chloride is used as solid absorbent and ammonia as refrigerant. A kind of consolidated composite material based on expanded graphite and strontium chloride is developed firstly, then the composite material is filled into the adsorption bed. The process of desorption or regeneration of strontium chloride is driven by solar energy, and the temperature range of the heating fluid is from 90 to 110℃, which can be heated by solar energy collected by low cost solar flat plate collectors. In the evaporation–absorption process, the evaporating temperature is between -10 and -35℃. The theoretical analysis shows that this refrigeration system is technical feasibility
Determination of Pb (Lead), Cd (Cadmium), Cr (Chromium), Cu (Copper), and Ni (Nickel) in Chinese tea with high-resolution continuum source graphite furnace atomic absorption spectrometry
AbstractThe contents of lead, cadmium, chromium, copper, and nickel were determined in 25 tea samples from China, including green, yellow, white, oolong, black, Pu'er, and jasmine tea products, using high-resolution continuum source graphite furnace atomic absorption spectrometry. The methods used for sample preparation, digestion, and quantificational analysis were established, generating satisfactory analytical precisions (represented by relative standard deviations ranging from 0.6% to 2.5%) and recoveries (98.91–101.32%). The lead contents in tea leaves were 0.48–10.57 mg/kg, and 80% of these values were below the maximum values stated by the guidelines in China. The contents of cadmium and chromium ranged from 0.01 mg/kg to 0.39 mg/kg and from 0.27 mg/kg to 2.45 mg/kg, respectively, remaining in compliance with the limits stipulated by China's Ministry of Agriculture. The copper contents were 7.73–63.71 mg/kg; only 64% of these values complied with the standards stipulated by the Ministry of Agriculture. The nickel contents ranged from 2.70 mg/kg to 13.41 mg/kg. Consequently, more attention must be paid to the risks of heavy metal contamination in tea. The quantitative method established in this work lays a foundation for preventing heavy metal toxicity in human from drinking tea and will help establish regulations to control the contents of heavy metals in tea
Studies on the properties and the thermal decomposition kinetics of natural rubber prepared with calcium chloride
To evaluate calcium chloride coagulation technology, two kinds of raw natural rubber samples were produced by calcium chloride and acetic acid respectively. Plasticity retention index (PRI), thermal degradation process, thermal degradation kinetics and differential thermal analysis of two samples studied. Furthermore, thermal degradation activation energy, pre-exponential factor and rate constant were calculated. The results show that natural rubber produced by calcium chloride possesses good mechanical property and poor thermo-stability in comparison to natural rubber produced by acetic acid.<br /
Analysis of Dynamic Characteristics of Pilots Under Different Intentions in Complex Flight Environment
Intention is the main embodiment of human cerebral conscious activities, which has an important influence on guiding the realization of human behaviour. It is a vital prerequisite for analysing the dynamic characteristics of pilots with different intentions. Considering the intention law of the generation, transfer and reduction, this paper analyses dynamic characteristics of pilots with different intentions, starting from the factors of effect on the intention. Taking airfield traffic pattern as an example for simulating flight experiments, the pilot’s multi-source dynamic data of human – aircraft – environment system under different intentions and their psycho-physiological-physical characteristics were recorded. Based on Matlab, one-way analysis of variance was used to extract variables with significant changes, and the variables under different intentions were compared and analysed. The results show that the conventional pilots are more conducive to control the aircraft to keep a stable flight attitude. This study is of great significance for perfecting the warning system of flight safety and improving the pilot’s micro-behaviour assessment system.</p
Universal factorial Schur -functions and their duals
We define universal factorial Schur -functions and their duals, which
specialize to generalized (co)-homology "Schubert basis" for loop spaces of the
classical groups. We also investigate some of their properties.Comment: 10 pages, old paper written in 2012.1
Pairing Symmetry in Iron-Pnictide Superconductor KFeAs
The pairing symmetry is one of the major issues in the study of iron-based
superconductors. We adopt a low-energy effective kinetic model based on the
first-principles band structure calculations combined with the -
model for KFeAs, the phase diagram of pairing symmetries is
constructed. Putting the values of and of the - model
obtained by the first-principles calculations into this phase diagram, we find
that the pairing symmetry for KFeAs is a nodal -wave in the
folded Brillouin zone with two iron atoms per unit cell. This is in good
agreement with experiments observed a nodal order parameter.Comment: 5 pages, 4 figures (The pairing symmetry is dependent on choosing an
effective tight-binding model. In the publication version, we adopt a
ten-orbital model by using the maximally localized Wannier functions based on
the first-principles band structure calculations, and give an s-wave pairing
for KFeAs
Behaviour of Sr, Ca, and Mg isotopes under variable hydrological conditions in high-relief large river systems
To assess how chemical weathering processes in large high-relief river systems respond to climatic variability, we studied seasonal changes in radiogenic strontium (87Sr/86Sr) and stable calcium (δ44/40Ca) and magnesium (δ26Mg) isotopes in the Jinsha and Yalong rivers, which drain the southeastern Tibetan Plateau. During the low-runoff season, with discharge (Q) 4000 m3/s), storms generate rapid overland flow, which transfers large volumes of soil into the rivers, such that soil weathering plays an important role in regulating riverine chemical compositions. At these times, the riverine Ca and Sr isotope evolution is influenced by secondary mineral dissolution and sediment–water cation exchange. Overall, this study highlights the potential of combining multiple isotope systems (Sr, Ca, Mg) to trace the dynamics of water–rock interaction under variable hydrological conditions
Probing two driven double quantum dots strongly coupled to a cavity
We experimentally and theoretically study a driven hybrid circuit quantum
electrodynamics (cQED) system beyond the dispersive coupling regime. Treating
the cavity as part of the driven system, we develop a theory applicable to such
strongly coupled and to multi-qubit systems. The fringes measured for a single
driven double quantum dot (DQD)-cavity setting and the enlarged splittings of
the hybrid Floquet states in the presence of a second DQD are well reproduced
with our model. This opens a path to study Floquet states of multi-qubit
systems with arbitrarily strong coupling and reveals a new perspective for
understanding strongly driven hybrid systems.Comment: 9 pages, 6 figure
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