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Low-temperature hydrogen production from natural gas via steam reforming requires novel processing concepts as well as stable catalysts. A process using zeolite membranes of the type MFI (Mobile FIve) was used to enrich natural gas with liquefied petroleum gas (LPG) alkanes (in particular, propane and n-butane), in order to improve the hydrogen production from this mixture at a reduced temperature. For this purpose, a catalyst precursor based on Rh single-sites (1 mol% Rh) on alumina was transformed in situ to a Rh1/Al2O3 catalyst possessing better performance capabilities compared with commercial catalysts. A wet raw natural gas (57.6 vol% CH4) was fully reformed at 650 &deg, C, with 1 bar absolute pressure over the Rh1/Al2O3 at a steam to carbon ratio S/C = 4, yielding 74.7% H2. However, at 350 &deg, C only 21 vol% H2 was obtained under these conditions. The second mixture, enriched with LPG, was obtained from the raw gas after the membrane process and contained only 25.2 vol% CH4. From this second mixture, 47 vol% H2 was generated at 350 &deg, C after steam reforming over the Rh1/Al2O3 catalyst at S/C = 4. At S/C = 1 conversion was suppressed for both gas mixtures. Single alkane reforming of C2&ndash, C4 showed different sensitivity for side reactions, e.g., methanation between 350 and 650 &deg, C. These results contribute to ongoing research in the field of low-temperature hydrogen release from natural gas alkanes for fuel cell applications as well as for pre-reforming processes.

The effects of graphene stacking are investigated by comparing the results of methane adsorption energy, electronic performance, and the doping feasibility of five dopants (i.e., B, N, Al, Si, and P) via first-principles theory. Both zigzag and armchair graphenes are considered. It is found that the zigzag graphene with Bernal stacking has the largest adsorption energy on methane, while the armchair graphene with Order stacking is opposite. In addition, both the Order and Bernal stacked graphenes possess a positive linear relationship between adsorption energy and layer number. Furthermore, they always have larger adsorption energy in zigzag graphene. For electronic properties, the results show that the stacking effects on band gap are significant, but it does not cause big changes to band structure and density of states. In the comparison of distance, the average interlamellar spacing of the Order stacked graphene is the largest. Moreover, the adsorption effect is the result of the interactions between graphene and methane combined with the change of graphene’s structure. Lastly, the armchair graphene with Order stacking possesses the lowest formation energy in these five dopants. It could be the best choice for doping to improve the methane adsorption.

External contamination sources (pesticide residues, heavy metals, solvent residues, and aflatoxin) and measurements and restriction standards that were published in previous studies, along with the authors' data were analyzed. It was found that the key to addressing the contamination is to place contamination source under control using mandatory standards.

In this paper, an algorithm based on traffic prediction is proposed, in bid to predict instantaneous traffic in ONU, guide higher-priority bandwidth allocation, and avoid "T+2" queuing delay. That is the Dynamic Bandwidth Allocation (Pre_DBA) for EPONs, which also includes a prediction corrected mechanism, to maximize bandwidth utilization. As is verified in the designed simulation, this algorithm, apart from ensuring effectiveness and fairness of the premise, is quite able to alleviate delay and jitter in higher-priority services as well.

With the development of micro/nano electronic technology and the miniaturization of IC (Integrated Circuit) packaging, the interfacial characteristics of the nanoscale interface structure in IC packaging become more and more serious on the whole performance of IC or devices. The aim of this article is to put forward a hybrid scale method to evaluate the interfacial thermal characteristics of the Cu/Al interface structure in IC packaging with Cu wires and Al pads. In this hybrid method, the EAM (Embedded Atom Method) potential is used to describe the Cu and Al atoms; the LJ (Lennard-Jones) potential is used to describe the Van der Waals force between Cu and Al atoms in MD (Molecular Dynamics) simulation at the nanoscale situation; meanwhile, the FE (Finite Element) and ISE (Interface Stress Element) are used to calculate the performance in the Micro/macroscales. It supplies a hybrid method to evaluate the interfacial properties in the IC packaging, which is helpful to design and manufacture of IC assembly.

In this paper the reliability of high power LED street lamp subjected to temperature cycle is analyzed. Two kinds of finite element models of LED street lamp structure with 60W input power are established by using ANSYS software. The temperature cycling condition from −5°Cto 50°C is loaded. The increasing and decreasing rate of temperature is 5°C / min and the holding time is 30 minutes. This process is consisted of 8 cycle periods and returns to room temperature 25°C for initial temperature. The results demonstrate the deformation of integrated LED street lamp structure can reach 2.17μm while that of LED lamp array is only 5nm. The results provide the basic for further study on LED street lamp failure mechanism and reliability design for LED street lamp.

In this paper, a novel thermal management method of vapor chamber printed circuit board coupled with sunflower heat sink is presented. The finite element method thermal analysis module of a 110 W multi-chip GaN-based white LED lamp is developed by ANSYS parametric design language and user interface design language, the thermal performance of the LED lamp thus can be analyzed more quickly and efficiently. The simulation results indicate that the overall design of the heat dissipation structure of the LED lamp is reasonable and the effect of heat dissipation is effective and satisfactory, the vapor chamber has higher heat transfer ability, and the sunflower heat sink is perfect for the heat dissipation of multi-chip LED lamp. Therefore, VCPCB coupled with sunflower heat sink is a powerful way for heat dissipation of high heat flux multi-chip GaN-based white LED lamps.

Based on the classic theoretical model of Diffusion-Limited Aggregation (DLA), two improved models, built for more practical use, were presented: Steps-Limited and Reaction-Limited three-dimensional Fractal Aggregation. The fractal dimension and porosity were calculated with cyclotron radius method, in order to study the influence of finite steps and reaction probability on the results of the fractal simulation of floc growth. A highly assembled aggregation would be formed as the Steps was getting smaller, contributing to the reduction of the cyclotron radius Rc which finally approached about 2.40, whose fractal characteristic became more and more inconspicuous. Smaller the reaction probability, the larger moving space of particles would be, resulted in the denser of the interior of the flocs, characterized by the gradual reduction of cyclotron radius Rc which finally approached about 2.65.

As the rapid development of technology, LED is gradually becoming the leader of lighting sources. Miner's lamp is the miner's eyes. Comparing with conventional miner's lamp, LED miner's lamp has many advantages such as less weight, less volume, higher luminous efficiency, greener, longer lifetime and son on. But heat dissipation of LED is still the bottle neck which limits the development of LED. LED miner' lamp contains two light sources which are main light source and secondary light source. This paper applied one integrated 3W COB white LED as the main light source and three 0.2W white LEDs as the secondary light source. Main light source and heat spreader are designed by building finite element models in this paper. The Models of different distance among chips, different number of fins, different height of fins and different shape of fins had been builded and analysed. It can be seen that within a certain range further distance among chips, more number of fins and higher height of fins would lead to lower junction temperature. Four shapes that are thin plate, cyclic thin plate, symmetrical square column and stagger square column had been analysed. It can be observed that the shape of symmetrical square column is the best, because the junction temperature of LED is the lowest. And cyclic thin plate is the second best, and stagger square column is the worst.

The current methods of preparation of pesticide residue analysis in traditional Chinese medicine were summarized in this paper. And the new preparation techniques used in recent years were reviewed, which included solid-phase micro-extraction (SPME), QuECHERS, matrix solid-phase dispersion (MSPD). In addition, the determination method of the pesticide residue methods in the traditional Chinese medicine were also included in the paper, and analysed the problem in the determination based on the characteristics of TCMs.

Compared with incandescent lamps and fluorescent lamps, nowadays LEDs (Light Emitting Diodes) are power saving, environment-friendly, and have the advantages of long lifetime and flexible color output. Therefore, LEDs are being widely used in many fields. In this paper, three high-power LEDs packaging modules with different packaging structures were selected to do the performance analysis based on the experiments. In the measurement, the LED junction temperature was controlled at seven levels (25°C, 50°C, 65°C, 75°C, 85°C, 95C, 100°C) in sequence. The thermal variation of some photoelectric parameters for LED packaging modules, such as forward voltage, relative flux output, correlated color temperature (CCT), color rending index (Ra), luminous efficiency and spectrum, were focused on and analyzed here. The experimental results demonstrated that the luminous flux, luminous efficacy and forward voltage of LEDs decreased with the increase of the junction temperature, but these three LEDs packaging modules have different varieties on CRI, CCT and spectrum. The related reasons were analyzed briefly in this paper.

In this paper, a 3 W high power LED array system with an in-line pin fin heat sink is designed, fabricated, and investigated for thermal transient analysis. Preliminary finite element simulation is conducted by ANSYS, and LED array average junction temperature is about 40.9°C. In the experiment, electrical test method is used to evaluate the heat dissipation effect of the LED array system. Experiment results show that the system works well. The cumulative thermal resistance of the system is about 6.7K/W, and corresponding LED array average junction temperature is about 40.5°C. It is found that the simulation result is consistent with the experimental result. The error is about 1%. It is also found that, in order to get accurate thermal resistance of every kind of material in the heat flow path, we should analyze the curves of cumulative and differential structure function simultaneously.

To ensure high reliability for advanced automotive electronics, investigation and understanding on the failure mechanisms under harsh conditions are needed. New methods and technologies for improved reliability and increased lifetime should be developed. In this paper, an investigation on the effect of high temperature aging on the thermomechanical properties, microstructure of the molding compounds and the reliability issues of the packages is presented. Experimental characterizations of aging effect on the packaging materials and the package were carried out. DMA, TMA and TGA were used to measure the moduli, coefficients of thermal expansion (CTE), and the shrinkage induced by the aging process. Construction analysis was performed to examine the aging effect on the microstructure of the aged samples. It is found that aging has significant influence on the rubbery modulus, the glass transition temperature (Tg) and the strength. Aging-induced shrinkage was also found. Oxidation is believed to be one of the main mechanisms for the degradation of the material properties.

In this paper, the high power LED system dissipation equipment is analyzed, in this LED system,consisting of nine chips and each chip is 3W. The novel dissipation equipment is design and analyzed, which is composed of vapor chamber, heat pipe array and fins. Vapor chamber as the thermal diffusion layer, it is effectively reduces the spreading resistance from LED chips to heat pipe. The other two models were built as the comparison. The designs were then being calculated on its transfer behavior using simulation with professional thermal analysis software Flotherm, simulation results show that the novel design has better heat dissipation ability than the other two comparison models, and the junction temperature is 71.6° C at the natural convection condition, after optimization of the fins, it is drop to 65.6° C.

To develop a GC method to determine the content of caryophyllene in Eupatorium fortune.The samples were determined on a DB-1701 (0.32 mm x 30 m, 0.25 microm) quartz capillary column. And the sample was extracted with ethanol by the ultrasonic assisted extraction.The calibration curve of caryophyllene is liner over the range of 0.002-2.0 g x L (-1) (R2 = 1). The recovery was from 96.76% to 104.15%.The method is accurate, simple with a good reproducibility. It can be used to control the quality of E. fortune.

A multiscale analysis method is put forward to evaluate the interfacial properties. The finite element method is used to estimate the thermodynamics properties of the Al-Cu interface structure in the macroscale, and the non-equilibrium molecular dynamics method is used to investigate the interfacial heat transfer in the nanoscale. The deformation and nanocracks always appear at the outside edge of interface owing to the dissimilar thermal expansion coefficients. The diffusion thickness of different atoms increases with the increase of temperature. The diffusion enhances the heat transfer with the increase of temperature in the nanoscale. The results reveal the mechanism of the interfacial heat transfer, which is helpful in the design and manufacture of IC assembly.

In order to investigate the electronic structures and optical properties of Al-doped ZnO materials, the characteristics such as band structure, density of states, complex dielectric constant of pure ZnO nanowires and Al-doped ZnO were studied by using first-principle method based on the density function theory (DFT). With the Al doping increasing, the band gap of Al-doped ZnO narrows, which is different from that of Al-doped ZnO nano-thin films. It supplies the theoretical reference value for the modulation of the band gap and optical properties of Al-doped ZnO.

In this paper, the reliability of LED luminaries system after thermal-ageing test was investigated with experimental test and numerical method. Samples were aged at 45oC, 85oC and 95oC using step-stress accelerated test. The thermal resistance was measured and the failure modes were verified. After 1,692 hours, four categories of failure modes were found and main failure mechanism was analysed. The total thermal resistance of sample C and D increased by 3.24 K/W and 5.09 K/W. The thermal stress is about 687 MPa, 1,106 MPa and 1,116 MPa at different ageing temperature.