Flow equation and similarity criterion during centrifugal casting in micro-channel

Liquid metal filling flow process in the microscale during the centrifugal casting process was studied by means of similar physical simulation. The research was focused on derived similarity criterion. Based on the traditional flow equations, the flow equation and the Bernoulli＇s equation for liquid metal flows in micro-scale space were derived, which provides a mathematical model for numerical simulation of micro-scale flow. In the meanwhile, according to the micro-flow equation and the similarity theory, the similarity criterion for the physical simulation of the mold filling behaviors was presented under centrifugal force field, so as to achieve the visual observation and quantitative analysis of micro-flow process.

TEM microstructure of rapidly solidified Mg-6Zn-1Y-1Ce alloy

Rapidly solidified（RS） Mg-6Zn-1Y-1Ce ribbons were prepared by single roller melt-spinning technique.Transmission electron microscopy and energy dispersive X-ray spectroscopy were employed to characterize the microstructure of RS ribbons.The results show that there is high density of particles distributed within grains and at grain boundaries in the region near wheel side.The particle density is decreased in the middle region and free surface region.The alloy is predominantly composed of supersaturated--Mg solid solution,T phase and W phase;meanwhile,a few icosahedral quasicrystalline and Mg4Zn7 particles are also observed.The T phase is confirmed having a body-centered orthorhombic structure that is transformed from the body-centered tetragonal structure Mg12Ce phase due to the partial substitution of Mg atoms by Zn.

Vector Correlations and Product Rotational Alignments of Reactions Ca+RBr→CaBr+R(R=CH_(3),C_(2) H_(5) and n-C_(3) H_(7))

The quasiclassical trajectory method is used to study the vector correlations of the reactions Ca＋RBr （R=CH3, C2H5 and n-C3H7Br） and the rotational alignment of product CaBr. The product rotational alignment parameters at different collision energies and the vector correlations between the reagent and product are numerically calculated. The vector correlations are described by using the angle distribution functions P（θr）, P（φr）, P（θr, φr） and the polarization-dependent differential cross sections （PDDCSs）. The peak values of P（θr） of the product CaBr from Ca＋CH3Br are larger than those from Ca＋C2H5Br and Ca＋n-C3H7Br. The peak of P（θr） at φr= 3π/2 is apparently stronger than that at φr= x/2 for the three reactions Ca＋RBr. The calculation results show that the rotational angular momentum of the product CaBr is not only aligned, but also oriented along the direction which is perpendicular to the scattering plane.The product CaBr molecules are strongly scattered forward. The orientation and alignment of the product angular momentum will affect the scattering direction of the product molecules to varying degrees.

Development of Bio-fertilizer Standard in China and Establishment of Standard System

Over the past decade,national standard and industry standard of bio-fertilizer have been gradually established in China. Moreover,the microbial fertilizer standard system with Chinese characteristics has been firstly established by China in the world. Development of bio-fertilizer standard,especially the amplification and modification of bio-fertilizer product standard and the construction of bio-fertilizer standard system,etc. were summarized in this paper. Meanwhile,relative suggestions of existing problems were put forward.

COMPARISON AND EVALUATION OF CURRENT REFERENCE GENERATION STRATEGIES FOR ACTIVE POWER FILTERS IN THREE-PHASE FOUR-WIRE SYSTEMS

For three phase four-wire active power filters （APFs）, several typical power theories and corresponding current reference generation strategies are induced, p-q, d-q, unify power factor （UPF） and instantaneous active current （IAC） methods are analyzed and compared with each other. The interpretation of active and reactive currents in non-sinusoidal and unbalanced three-phase four-wire systems is given based on the generalized instantaneous reactive power theory. The performance and the characteristic are evaluated, and the application conditions of current reference generation strategies are concluded. Simulation results under different source voltages and loads verify the evaluation result.

A Fractional-N CMOS DPLL with Self-Calibration

A digital phase-locked loop （DPLL） based on a new digital phase-frequency detector is presented. The self-calibration technique is employed to acquire wide lock range,low jitter, and fast acquisition. The DPLL works from 60 to 600MHz at a supply voltage of 1.8V. It also features a fraetional-N synthesizer with digital 2nd-order sigma-delta noise shaping, which can achieve a short lock time,a high frequency resolution,and an improved phase-noise spectrum. The DPLL has been implemented in SMIC 0. 18μm 1.8V 1P6M CMOS technology. The peak-to-peak jitter is less than 0. 8% of the output clock period and the lock time is less than 150 times of the reference clock period after the pre-divider.

Icosahedral quasicrystal phase in Mg-Zn-Y-(Zr) alloys:A review

Magnesium alloys possess lots of unique advantages as one of the most promising materials. However, relatively poor mechanical properties limit the application of Mg alloys. As a relatively excellent strengthing phase, icosahedral quasicrystal phased-phase） has great influence on Mg-Zn-Y-（Zr） alloys. The yield strength of Mg-Zn-Y-（Zr） alloys could reach 150 - 450 MPa at room temperature with different I-phase volume fractions, therefore the formation of I-phase has been regared as an effective method to improve the performance of Mg alloys. In this review paper, a series of researches about the Mg-Zn-Y-（Zr） alloys containing I-phase have been discussed, mainly including the current understandings about formation mechanism and I- phase structure, its orientation relationship with a-Mg matrix, and the effect of I-phase on Mg-Zn-Y-（Zr） alloys.

Effect of Mg-based spherical quasicrystal on microstructures and mechanical properties of ZA54 alloy

To improve the strength, toughness and heat-resistance of magnesium alloy, the microstrucmre and mechanical properties of ZA54 alloy reinforced by icosahedral quasicrystal phase （/-phase） particles were studied. Except α-Mg, φ-phase and τ-phase, MgZnYMn I-phase particles can be obtained in ZA54-based composites by the addition of icosahedral quasicrystal-contained Mg-Zn-Y-Mn master alloy. The introduction of MgZnYMn I-phase into ZA54 alloy has great contribution to the refinement of matrix microstructures and the improvement of mechanical properties. When the addition of Mg-based spherical quasicrystal master alloy is up to 3.5% （mass fraction）, the macro-hardness of ZA54-based composites is increased to HB 68. The impact toughness of composites reaches the peak value of 18.3 J/cm^2, which is about 29% higher than that of ZA54 mother alloy. The highest tensile properties at ambient and elevated temperatures with master alloy addition of 2.5% （473 K） are also obtained in ZA54-based composites with 3.5% （mass fraction） Mg-Zn-Y-Mn master alloy addition. The ultimate tensile strength of composites at ambient and elevated temperatures are 192.5 MPa and 174 MPa, which are 23.4% and 33.8% higher than that of ZA54 mother alloy, respectively. The improved mechanical properties are mainly attributed to the pinning effect of I-phase on grain boundaries.

Phase transformation behavior of Al_9(Mn,Ni)_2 eutectic phase during heat treatment at 600°C in Al-4Ni-2Mn alloy

The morphology evolution and phase transformation of Al9(Mn,Ni)2 eutectic phase in an Al-4Ni-2Mn alloy during heat treatment at 600°C were studied by scanning electron microscopy(SEM)and transmission electron microscopy(TEM).Results show that nearly all of the eutectic fibers change into prolate ellipsoid and spherical particles in the process of heat treatment,and Ostwald ripening phenomenon occurs in the eutectic region with the increase of the heat treatment time.Besides,a phase transformation from Al9(Mn,Ni)2 to O-phase is confirmed.The morphologies of the transformed particles indicate that the O-phase preferentially nucleates on the specific crystal plane of the Al9(Mn,Ni)2 eutectic phase and grows in a certain direction.During the phase transformation,the(010)[001]slip system in O-phase is activated,and the resultant slip traces appear on the surface of some O-phase particles.

Short-term effectiveness of radiochemoembolization for selected hepatic metastases with a combination protocol

AIM： To introduce the combination method of radio- chemoembolization for the treatment of selected he- patic metastases. METHODS： Twenty patients with biopsy proven hepat- ic metastases were selected from those who underwent transarterial radiochemoembolization, a novel combina- tion protocol, between .lanuary 2009 and July 2010. Patients had different sources of liver metastasis. The treatment included transarterial administration of three chemotherapeutic drugs （mitomycin, doxorubicin and cisplatin）, followed by embolization with large （50-150 μm） radioisotope particles of chromic 32R Multiphasic computer tomography or computer tomography stud- ies, with and without contrast medium injections, were performed for all patients for a short-term period before and after the treatment sessions. The short-term effec- tiveness of this procedure was evaluated by modified response evaluation criteria in solid tumors （mRECIST）, which also takes necrosis into account. The subjective percentage of necrosis was also assessed. The re- sponse evaluation methods were based on the changes in size, number, and the enhancement patterns of the lesions between the pre- and post-treatment imaging studies. RESULTS： Patients had liver metastasis from colorectal carcinomas, breast cancer, lung cancer and carcinoid tumors. The response rate based on the mRECIST criteria was 5% for complete response, 60% for par- tial response, 10% for stable disease, and 25% for progressive disease. Regarding the subjective necrosis percentage, 5% of patients had complete response, 50% had partial response, 25% had stable disease, and 20% had progressive disease. Based on traditional RECIST criteria, 3 patients （15%） had partial response, 13 patients （65%） had stable disease, and 4 patients （20%） had disease progression. In most patients, colorectal carcinoma was the source of metastasis （13 patients）. Based on the mRECIST criteria, 8 out of these 13 patients had partial responses, while one remained stable, and 5 showed progressive disease. We also had 5 cases of breast cancer metastasis which mostly remained stable （4 cases）, with only one partial response after the procedure. Six patients had bilobar involvement; three of them received two courses of radiochemoembolization. The follow up imaging study of these patients was performed after the second ses- sion. In the studied patients there was no evidence of extrahepatic occurrence, including pulmonary radioac- tive deposition, which was proven by Bremsstrahlung scintigraphy performed after the treatment sessions. For the short-term follow-ups for the 2 mo after the therapy, no treatment related death was reported. The mostly common side effect was post-embolization syndrome, presented as vomiting, abdominal pain, and fever. Nineteen （95%） patients experienced this syndrome in different severities. Two patient had asci- tes （with pleural effusion in one patient） not related to hepatic failure. Moreover, no cases of acute liver failure, hepatic infarction, hepatic abscess, biliary necrosis, tu- mor rupture, surgical cholecystitis, or non-targeted gut embolization were reported. Systemic toxicities such as alopecia, marrow suppression, renal toxicity, or cardiac failure did not occur in our study group. CONCLUSION： Radiochemoembolization is safe and effective for selected hepatic metastases in a short- term follow-up. Further studies are required to show the long-term effects and possible complications of this approach.

BiScO_(3)-BiFeO_(3)-PbTiO_(3)-BaTiO_(3) high-temperature piezoelectric ceramic and its application on high-temperature acoustic emission sensor

Piezoelectric ceramic based high-temperature acoustic emission(AE)sensor is required urgently in the structural health monitoring of high-temperature fields.In this research,a series of 0.45(BiSc_(x)O_(3)-BiFe_(1-x)O_(3))-0.48PbTiO_(3)-0.07BaTiO_(3)(BSc_(x)Fe_(1-x)-PT-BT,n(Sc)/n(Fe)=0.4/0.6-0.6/0.4)ceramics with both high Curie temperature and large piezoelectric constant were presented.The structure and electrical properties of BSc_(x)Fe_(1-x)-PT-BT ceramics as a function of n(Sc)/n(Fe)have been systematically investigated.All the ceramics possess a perovskite structure,and the phase approaches from the rhombohedral toward the tetragonal phase with the decrease of n(Sc)/n(Fe).The BSc_(0.5)Fe_(0.5)-PT-BT and BSc_(0.5)Fe_(0.5)-PT-BT piezoelectric ceramics exhibit good piezoelectricity(d_(33)=250-281 pC/N),high Curie temperature(T_(C)=430-450℃)and excellent temperature stability.These improvements are greatly attributed to the balance between rhombohedral and tetragonal phase near morphotropic phase boundary with dense microstructure of ceramics.AE sensor based BSc_(0.5)Fe_(0.5)-PT-BT piezoelectric ceramic was designed,prepared and tested.The high-temperature stability of AE sensor was characterized through pencil-lead breaking with in situ high-temperature test.The noise of AE sensor is less than 40 dB,and the acoustic signal is up to 90 dB at 200℃.As a result,AE sensors based on BSc_(x)Fe_(1-x)-PT-BT piezoelectric ceramics are expected to be applied into the structural health monitoring of high temperature fields.

Klein Paradox and Disorder-Induced Delocalization of Dirac Quasiparticles in One-Dimensional Systems

Dirac particle penetration is studied theoretically with Dirac equation in one-dimensional systems. We investigate a one-dimensional system with N barriers where both barrier height and well width are constants randomly distributed in certain range. The one-parameter scaling theory for nonrelatiyistic particles is still valid for massive Dirac particles. In the same disorder sample, we find that the localization length of relativistic particles is always larger than that of nonrelativistic particles and the transmission coefficient related to incident particle in both cases fits the form T～ exp（-αL）. More interesting, massless relativistic particles are entirely delocalized no matter how big the energy of incident particles is.

A Target-Orientated Marker Image Binarization Method for Orthopaedic Surgical Navigation System

Camera calibration is the key technique in a C-arm based orthopaedic surgical navigation system. The extraction of marker location information is a necessary step in the calibration process. Ideal marker images should possess uniform background and contain marker shadow only, but in fact marker images always possess nonuniform background and are contaminated by noise and unwanted anatomic information, making the extraction very difficult. A target-orientated marker shadow extraction method was proposed. With this method a proper threshold for marker image binarization can be determined.

Evolution of Dark Spatial Soliton in Quasi-phase-matched Quadratic Media

We theoretically investigate the evolvement of dark spatial soliton withcascading quadratic nonlinearity in quasi-phase-matched second harmonic generation. It is shown thatthe dark solitary wave can propagate stably when background intensity is large enough, in whichdiffraction of beam can be balanced by the cascading quadratic nonlinearity. We also analyze theinfluence of phase-mismatch on the stabihty of dark soliton propagation.

The Relevance of International Financial Reporting Standards for Small and Medium-Sized Entities （IFRS for SMEs） in Swaziland

The purpose of this study is to explore the relevance of adopting International Financial Reporting Standards （IFRS） for small and medium-sized entities （SMEs） in Swaziland. The study further seeks to determine if IFRS for SMEs can be the solution to better reporting by local SMEs. There has been a growing need for different reporting standards for small firms and big firms over the years due to the unique challenges and attributes they face especially in the area of financial reporting. This research is based on a statistical analysis of questionnaires completed by accountants from SMEs in Swaziland as well as other stakeholders who have a direct or an indirect interest in the financial statements of SMEs. These stakeholders included audit firms and the financial institutions. The sampling rate of 10% was applied across each industry to come up with a sample of 60 SMEs. Furthermore, a 100% sampling rate on the other stakeholders was applied. These were nine financial institutions and eight audit finns. The findings from the study revealed that SMEs in Swaziland are having challenges with the current reporting framework but to some extent, the framework is suitable. Most SMEs are not aware of IFRS for SMEs, therefore the accounting profession in Swaziland （SIA） has a huge role to play in training auditors and accountants in the country. Overall, IFRS for SMEs is applicable in Swaziland.

A Σ-Δ Fractional-N PLL Frequency Synthesizer with AFC for SRD Applications

A fractional-N frequency synthesizer for 433/868MHz SRD applications is implemented in a 0.3μm CMOS process. A wide-band VCO and an AFC are used to cover the desired bands. A 3bit third order sigma-delta modulator is adopted to reduce the out-band phase noise. The measurements show a VCO tuning range from 1.31 to 1.88GHz with AFC working correctly,an out-band phase noise of -139dBc/Hz at 3MHz offset frequency, and a fractional spur of less than - 60dBc. The chip area is 1.5mm × 1.2mm and the total current dissipation including LO buffers is 19mA from a single 3.0V supply voltage.

Determination of Lignin in Marine Sediment Using Alkaline Cupric Oxide Oxidation-Solid Phase Extraction-on-Column Derivatization-Gas Chromatography

Lignin serves as one of the most important molecular fossils for tracing Terrestrial Organic Matters （TOMs） in marine environment. Extraction and derivatization of lignin oxidation products （LOPs） are crucial for accurate quantification of lignin in marine sediment. Here we report a modification of the conventional alkaline cupric oxide （CuO） oxidation method, the modification consisting in a solid phase extraction （SPE） and a novel on-column derivatization being employed for better efficiency and reproducibility. In spiking blanks, recoveries with SPE for the LOPs are between 77.84% and 99.57% with relative standard deviations （RSDs） ranging from 0.57% to 8.04% （n=3）, while those with traditional liquid-liquid extraction （LLE） are from 44.52% to 86.16% With RSDs being from 0.53% to 13.14% （n=3）. Moreover, the reproducibility is greatly improved with SPE, with less solvent consumption and shorter processing time. The average efficiency of on-column derivatization for LOPs is 100.8%±0.68%, which is significantly higher than those of in-vial or in-syringe derivatization, thus resulting in still less consumption of derivatizing reagents.Lignin in the surface sediments sampled from the south of Yangtze River estuary, China, was determined with the established method. Recoveries of 72.66% to 85.99% with standard deviation less than 0.01mg/10g dry weight are obtained except for p-hydroxybenzaldehyde. The lignin content ∑8 （produced from 10g dry sediment） in the research area is between 0.231 and 0.587mg. S/V and C/V ratios （1.028 ± 0.433 and 0.192±0.066, respectively） indicate that the TOMs in this region are originated from a mixture of woody and nonwoody angiosperm plants; the high values or （Ad/Al）v suggest that the TOMs has been highly degraded.

θ-PSO: a new strategy of particle swarm optimization

Particle swarm optimization (PSO) is an efficient, robust and simple optimization algorithm. Most studies are mainly concentrated on better understanding of the standard PSO control parameters, such as acceleration coefficients, etc. In this paper, a more simple strategy of PSO algorithm called θ-PSO is proposed. In θ-PSO, an increment of phase angle vector replaces the increment of velocity vector and the positions are decided by the mapping of phase angles. Benchmark testing of nonlinear func- tions is described and the results show that the performance of θ-PSO is much more effective than that of the standard PSO.

A Multi-Hop Moving Zone(MMZ) Clustering Scheme Based on Cellular-V2X

A clustering scheme based on pure V2V communications has two prominent issues i.e. broadcast storm and network disconnection. The application of the fifth generation(5G) technology to vehicular networks is an optimal choice due to its wide coverage and low latency features. In this paper, a Multihop Moving Zone(MMZ) clustering scheme is proposed by combining IEEE 802.11p with the 3rd Generation Partnership Project(3GPP) 5G cellular technology. In MMZ, vehicles are clustered up-to three hops using V2V communications based on IEEE 802.11 p aiming to reduce excessive cellular hand-off cost. While the zonal heads(ZHs) i.e. cluster heads(CHs) are selected by cellular-V2X(C-V2X) on the basis of multi-metrics i.e. relative speed, distance and link life time(LLT). The main goal of MMZ is to form stable clusters achieving high packet delivery and low latency. The simulation results using ns3 show that, 5G wide range technology significantly improves the stability of MMZ in term of ZH duration and change rate. The average Data Packet Delivery Ratio(DPDR) and E2E latency are also improved as compared to the existing clustering schemes.

On-line Separation and Preconcentration for Histamine Determination in Fish Meal Using Cation-Exchanger Resin

FI system was used for the determination of histamine. A mini-column filled with amberlite resin （weak cation exchanger） was introduced to the flow system. A 200 laL of the sample was injected into the carrier stream through the injection valve. The merged streams were passed through a quartz flow cell in a spectrophotometer connected to recorder. Under the optimum conditions, the calibration curve was linear in the range 0.02-1.5 μg mL^-1 of histamine using the peak height as an analytical signal, while the detection limit was 0.01 μg mL^-1. The precision and accuracy of the method were studied depending upon the values of the relative standard deviation and relative error percentage. The selectivity of the method was investigated by studying the effect of interference from other species accompanied with histamine in fish meal. Under the optimum conditions, the system was used for on line separation, preconcentration of histamine. The proposed method was applied for the determination of histamine in fish meal. The results were compared with the standard method and a good agreement between the results was obtained.