Digital management technology and its application to investment casting enterprises

With the advent of Industry 4.0, more and more investment casting enterprises are implementing production manufacturing systems, especially in the last two years. This paper summarizes three new common requirements of the digital management aspect in precision casting enterprises, and puts forward three corresponding techniques. They are: the production process tracking card technology based on the main-sub card mode; the workshop site production process processing technology based on the barcode; and the equipment data integration technology. Then, this paper discusses in detail the principle, application and effect of these technologies; to provide the reference for enterprises to move towards digital casting and intelligent casting.

Catastrophe Model of Steam Flow Excitation Vibration in Steam Turbine Governing Stage

汽流激振是影响大型汽轮机组安全运行的主要故障之一。根据突变理论、非线性振动理论以及流体动力学，从机理分析的角度出发，对汽轮机调节级在部分进汽下导致的汽流激振突变性能进行了定量分析。建立了部分进汽情况下调节级气流激振力模型，以及考虑汽流激振力的调节级非线性动力学模型，通过基于突变理论的推导，得到了调节级汽流激振的尖点突变流形和分岔集，确定了系统汽流激振突变的影响因子，讨论了振幅突变与影响因子的相关性，划分了系统工作的突变区域。最后，利用数值计算方法对汽流激振的幅值响应进行了分析，分析结果验证了基于突变理论的汽流激振突变分析方法的正确性。研究成果为汽轮机汽流激振突变性能的研究提供了一条新的途径。

Research and application of enterprise resource planning system for foundry enterprises

PPDB issues-four aspects of current management issues of foundry enterprises are discussed in this paper,including Production Management,Process Control,Duration Monitoring and Business Intelligence Data Analysis.Also a whole Enterprise Resource Planning(ERP) solution for foundry enterprises is proposed.The solution contains many models,four of which are used to solve the PPDB issues.These are called SPDB models,which separately are the Single-piece management model(based on casting lifecycle),Process management model(based on task-driven technology),Duration monitoring model(based on surplus period),and Business intelligence data analysis model(based on data mining).An ERP system for foundry enterprises,named HZERP,was researched and developed,and applied to a sand casting company of single piece and small batch production.Qualitatively and quantitatively comparing the application effect before and after implementing the HZERP system,the result demonstrated that the foundry ERP system based on the SPDB models can help metal casting enterprises achieve the single-piece management,better regulate the production processes,improve production and delivery management,shorten the production cycle,reduce costs,and speed up the capital turnover to a large extent.

Biologically Inspired Self-assembling Synthesis of Bone-like Nano-hydroxyapatite/PLGA-(PEG-ASP)_n Composite: A New Biomimetic Bone Tissue Engineering Scaffold Material

A new biomimetic bone tissue engineering scaffold material, nano-HAI PLGA-（ PEG-Asp ）n composite, was synthesized by a biologically inspired self-assembling approach. A novel biodegradable PLGA- （ PEG-Asp ）n copolymer with pendant amine functional groups and enhanced hydrophilicity woo synthesized by bulk ring-opening copolymerization by DL-lactide（ DLLA） and glycolide（ GA ） with Aspartic acid （ Asp ）-Polyethylene glycol（PEG） alt-prepolymer. A Three-dimensional, porous scaffold of the PLGA-（ PEG- Asp）n copolymer was fabricated by a solvent casting , particulate leaching process. The scaffold woo then incubated in modified simulated body fluid （naSBF）. Growth of HA nanocrystals on the inner pore surfaces of the porous scaffold is confirmed by calcium ion binding analyses, SEM , mass increooe meoourements and quantification of phosphate content within scaffolds. SEM analysis demonstrated the nucleation and growth of a continuous bonelike, low crystalline carbonated HA nanocrystals on the inner pore surfaces of the PLGA- （ PEG-Asp ）n scaffolds. The amount of calcium binding, total mass and the mass of phosphate on experimental PLGA- （ PEG-Asp ） n scaffolds at different incubation times in mSBF was significantly greater than that of control PLGA scaffolds. This nano-HA/ PLGA-（ PEG- Asp ）n composite stunts some features of natural bone both in main composition and hierarchical microstrueture. The Asp- PEG alt-prepolymer modified PleA copolymer provide a controllable high surface density and distribution of anionic functional groups which would enhance nucleation and growth of bonelike mineral following exposure to mSBF. This biomimetic treatment provides a simple method for surface functionalization and sabsequent mineral nucleation and self-oosembling on bodegradable polymer scaffolds for tissue engineering.

Effects of durotomy versus myelotomy in the repair of spinal cord injury

Current management for spinal cord injury aims to reduce secondary damage and recover sensation and movement.Acute spinal cord injury is often accompanied by spinal cord compartment syndrome.Decompression by durotomy and/or myelotomy attempts to relieve secondary damage by completelyrelieving the compression of the spinal cord,removing the necrotic tissue,decreasing edema,reducing hemorrhage,and improving blood circulation in the spinal cord.However,it is controversial whether durotomy and/or myelotomy after spinal cord injury are beneficial to neurological recovery.This review compares the clinical effects of durotomy with those of myelotomy in the treatment of spinal cord injury.We found that durotomy has been performed more than myelotomy in the clinic,and that durotomy may be safer and more effective than myelotomy.Durotomy performed in humans had positive effects on neurological function in 92.3% of studies in this review,while durotomy in animals had positive effects on neurological function in 83.3% of studies.Myelotomy procedures were effective in 80% of animal studies,but only one clinical study of myelotomy has reported positive results,of motor and sensory improvement,in humans.However,a number of new animal studies have reported that durotomy and myelotomy are ineffective for spinal cord injury.More clinical data,in the form of a randomized controlled study,are needed to understand the effectiveness of durotomy and myelotomy.

Protective effect of propofol preconditioning and postconditioning against ischemic spinal cord injury

Propofol preconditioning has been shown to provide neuroprotection against spinal ischemia/reperfusion injury. In this study, spinal cord ischemia/repeffusion injury was induced by blocking the abdominal aorta in rabbits for 40 minutes. Results showed that the co-application of propofol preconditioning and postconditioning regimen ameliorated pathological injury of the ischemic spinal cord and suppressed the elevation of malondialdehyde levels and increased superoxide dismutase activities in the spinal cord tissues. Co-application of propofol preconditioning and postconditioning resulted in potent protective effects against spinal cord ischemia/reperfusion injury and prolonged the spinal cord＇s tolerance to ischemia. This protection was associated with the anti-lipid peroxidation capacity of the spinal cord tissues.

Investigation of Al2O3 and Fe2O3 transmission and transformation during the decomposition of phosphogypsum

Phosphogypsum(PG) is a solid waste produced in the phosphate fertilizer industry and is environmentally harmful.The decomposition of PG to recycle calcium and sulfur is a proper way to reutilize PG. Current work aims at enriching the basic theory of coal decomposition process of PG. The emphasis was laid on the exploration of impact of main impurities on the process. On the other hand, according to Reaction Module, Equilib Module, and Phase Diagram Module of FactS age, the simulation computation was done on the systems of pure gypsum mixed with coal,with or without impurities for avoiding other impurities interference. Later, possible reactions in the process were deduced. Additionally, experiments were conducted in a TG-DTA integrated thermal gravimetric analyzer and a tube furnace. The products from the experiments were characterized and analyzed to verify the accuracy of theoretical calculations. The results showed that these impurities can change the decomposition process of PG. For example, aluminum oxide was transformed to calcium sulfoaluminate, while iron oxide was transformed to dicalcium ferrite. Furthermore, the results help to further improve the basic theory of phosphogypsum decomposition.

BIFURCATIONS OF A CANTILEVERED PIPE CONVEYING STEADY FLUID WITH A TERMINAL NOZZLE

This paper studies interactions of pipe and fluid and deals with bifurcations of a cantilevered pipe conveying a steady fluid, clamped at one end and having a nozzle subjected to nonlinear constraints at the free end. Either the nozzle parameter or the flow velocity is taken as a variable parameter. The discrete equations of the system are obtained by the Ritz-Galerkin method. The static stability is studied by the Routh criteria. The method of averaging is employed to investigate the stability of the periodic motions. A Runge-Kutta scheme is used to examine the analytical results and the chaotic motions. Three critical values are given. The first one makes the system lose the static stability by pitchfork bifurcation. The second one makes the system lose the dynamical stability by Hopf bifurcation. The third one makes the periodic motions of the system lose the stability by doubling-period bifurcation.

Change of BMD after Weaning or Resumption of Menstruation in Chinese Women with Different FokI VDR-genotypes:A Randomized,Placebo-controlled,Calcium Supplementation Trial

Objective To investigate the effect of calcium supplementation on bone mineral density （BMD） in Chinese women with different Fokl vitamin D receptor （VDR） genotypes （FF, Ff, and ff） after weaning or resumption of menstruation during lactation. Methods A total of 40 subjects with the same Fokl VDR genotype were randomly divided into two groups： one received calcium tablet （600 mg once daily as CaCO3） and the other placebo tablet once daily for 1 year. At baseline, BMD was measured by dual-energy X-ray absorptiometry at lumbar spine （L2-L4） and at left hip whereas serum PICP, serum OC, and urinary CTX, serum 25（OH）VitD3, and serum estradiol were measured at weaning and I year thereafter. Results After the intervention, BMD at lumbar spine and at left hip increased significantly in all these women with a trend among different Fokl VDR genotypes such as FF 〉 Ff 〉 ff （P〈O.05, 〈0.01, and 〈0.001, respectively）. BMD at lumbar spine in women with FF VDR genotype increased much more rapidly than in those with ff VDR genotype （P〈0.05）. Compared with the control group women with the FF genotype regained more BMD after calcium supplementation （P〈0.05）. Conclusion Daily calcium 600 mg supplementation has beneficial effect on the bone health of women with FF VDR genotype.

Research on testing method of resin sand high temperature compressive strength

High temperature compressive strength is one of the most important performances of resin sand; its value directly concerns the quality of castings. In order to seek the best testing method of resin sand high temperature compressive strength, a self-developed instrument was used to carry out experiments, and the sample shape and size were designed and studied. The results show that a hollow cylinder sample can reflect the strength difference of different resin sands better than a solid cylinder sample, and its data is stable. The experiments selected Φ20/5×30 mm as the size of the hollow cylinder samples. The high temperature compressive strengths of phenol-formaldehyde resin coated sand, furan resin self-setting sand, and TEA resin sand were each tested. For the resin sand used for cast steel and cast iron, 1,000 oC was selected as the test temperature; for the resin sand used for cast non-ferrous al oy, 800 oC was selected as the test temperature; and for all the resin sand samples, 1 min was selected as the holding time. This testing method can truthfully reflect the high temperature performance of three kinds of resin sand; it is reproducible, and the variation coefficients of test values are under 10%.

Effects of Portulaca Oleracea on Insulin Resistance in Rats with Type 2 Diabetes Mellitus

Objective: To study the effects of Portulaca oler acea, a Chinese medicinal herb, on insulin resistance in rats with type 2 diabet es mellitus (T2DM). Methods: Experimental model of T2DM was established by injection of streptozotocin (25mg/kg) and feeding with high calorie forage. The effects o f Portulaca oleracea on oral glucose tolerance, serum levels of insulin, triglyc eride, total cholesterol, high density lipoproteins cholesterol and free f atty acids, and insulin sensitivity index were all observed. Results: Portulaca oleracea could reduce the body weight, improve the impaired glucose tolerance and lipid metabolism, decrease serum free fatty acids, attenuate hyperinsulinemia and elevate insulin sensitivity. Conclusion: Portulaca oleracea could improve insulin resistance i n rats with T2DM, and the mechanism might be related to its actions in improving lipid metabolism and decreasing free fatty acids.

Preparation and study on performance of submicron nickel powder for multilayer chip positive temperature coefficient resistance

Base metal nickel is often used as the inner electrode in multilayer chip positive temperature coefficient resistance （PTCR）. The fine grain of ceramic powders and base metal nickel are necessary. This paper uses reducing hydrazine to gain submicron nickel powder whose diameter was 200-300 nm through adjusting the consumption of nucleating agent PVP properly. The submicron nickel powder could disperse well and was fit for co--fired of multilayer chip PTCR. It analyes the submicron nickel powder through x-ray Diffraction （XRD） and calculates the diameter of nickel by PDF cards. Using XRD analyses it obtains several conclusions： If the molar ratio of hydrazine hydrate and nickel sulfate is kept to be a constant, when enlarging the molar ratio of NaOH/Ni^2＋, the diameter of nickel powder would become smaller. When the temperature in the experiment raises to 70-80 ℃, nickel powder becomes smaller too. And if the molar ratio of NaOH/Ni2＋ is 4, when molar ratio of （C2H5O）2/Ni^2＋ increases, the diameter of nickel would reduce. Results from viewing the powders by optical microscope should be the fact that the electrode made by submicron nickel powder has a better formation and compactness. Furthermore, the sheet resistance testing shows that the electrode made by submicron nickel is smaller than that made by micron nickel.

Tensile properties and microstructure of rheo-diecast 7075 alloy prepared by serpentine channel process

A semisolid slurry of 7075 aluminum alloy was prepared by means of a serpentine channel process (SCP) and rheo-diecasting. The influences of pouring temperature during slurry preparation, the injection pressure and die preheat temperature on the mechanical properties and microstructure of a rheo-diecast 7075 aluminum alloy were investigated. The results show that the as-cast strength and elongation of the tensile samples were 210-260 MPa and 0.2%-1.7%, respectively, with an injection pressure of 130 MPa, a pouring temperature of 700-720℃, a preheat temperature of 280-350℃, and a plunger speed of 0.5 m·S^-1. The results also show that the aged strength and elongation of the tensile samples were 420-453 MPa and 1.0%-1.4%, respectively, when the alloy solution was treated at 470℃ for 12 h and aged at 120℃ for 24 h. The substantial shrinkage porosity in the 7075 aluminum alloy tensile samples was the main cause of low elongation.

PROGNOSTIC SIGNIFICANCE OF EXPRESSION OF SURVIVIN IN ACUTE LEUKEMIA

Objective: To investigate the expression of survivin gene and its significance in acute leukemia. Methods: The expression of surviving in 134 acute leukemia patients and 4 leukemia cell lines was detected by RT-PCR and immunofluorescence analysis. Results: We detected survivin expression in 78 of 134 acute leukemia patients and all the cell lines but not in normal controls and anemia patients. Survivin gene expression correlated with a lower white blood cell count, which was 11×109/L and 48×109/L in the positive and negative group respectively (P<0.01 by the Mann-Whitney test). In 55 cases of FAB M1/M2/M3, it was associated with leukemic cell maturation(P<0.01 by the Fisher test). Survivin expression was strongly related to survival time of acute leukemia patients (P<0.05). Conclusion: These data suggest that survivin expression may be considered as a new unfavorable prognostic factor for acute leukemia due to its important role in apoptosis inhibition that influences disease outcome.

Propofol protects against blood-spinal cord barrier disruption induced by ischemia/reperfusion injury

Propofol has been shown to exert neuroprotective effects on the injured spinal cord.However,the effect of propofol on the blood-spinal cord barrier（BSCB） after ischemia/reperfusion injury（IRI） is poorly understood.Therefore,we investigated whether propofol could maintain the integrity of the BSCB.Spinal cord IRI（SCIRI） was induced in rabbits by infrarenal aortic occlusion for 30 minutes.Propofol,30 mg/kg,was intravenously infused 10 minutes before aortic clamping as well as at the onset of reperfusion.Then,48 hours later,we performed histological and m RNA/protein analyses of the spinal cord.Propofol decreased histological damage to the spinal cord,attenuated the reduction in BSCB permeability,downregulated the m RNA and protein expression levels of matrix metalloprotease-9（MMP-9） and nuclear factor-κB（NF-κB）,and upregulated the protein expression levels of occludin and claudin-5.Our findings suggest that propofol helps maintain BSCB integrity after SCIRI by reducing MMP-9 expression,by inhibiting the NF-κB signaling pathway,and by maintaining expression of tight junction proteins.

High expression of osteoglycin decreases gelatinase activity of murine hepatocarcinoma Hca-F cells

AIM:To investigate the possible correlation between osteoglycin expression and gelatinase activity of mouse hepatocarcinoma Hca-F cells.METHODS:A eukaryotic expression plasmid pIRE Spuro3 osteoglycin(+)was constructed and transfected into Hca-F cells to investigate the possible correlation between osteoglycin expression and gelatinase activity of Hca-F cells cultured with extract of lymph node,liver,spleen or in DMEM medium.The activity of gelatinases was examined through zymographic analysis.RESULTS:High expression of osteoglycin attenuated the gelatinase activity of Hca-F cells cultured with extract of lymph node,and at the same time,decreased the metastatic potential of Hca-F cells to peripheral lymph nodes in vivo.CONCLUSION:High expression of osteoglycin decreases the gelatinase activity of Hca-F cells cultured with extract of lymph node;regulation of gelatinase activity might be one of mechanisms that osteoglycin contributes to lymphatic metastasis suppression.

Power dissipation characteristics of great power and super high speed semiconductor switch

The power dissipation characteristics of pulsed power switch reversely switched dynistors （RSDs） are investigated in this paper. According to the expressions of voltage on RSD, derived from the plasma bipolar drift model and the RLC circuit equations of RSD main loop, the simulation waveforms of current and voltage on RSD are acquired through iterative calculation by using the fourth order Runge-Kutta method, then the curve of transient power on RSD versus time is obtained. The result shows that the total dissipation on RSD is trivial compared with the pulse discharge energy and the commutation dissipation can be nearly ignored compared with the quasi-static dissipation. These characteristics can make the repetitive frequency of RSD increase largely. The experimental results prove the validity of simulation calculations. The influence factors on power dissipation are discussed. The power dissipation increases with the increase of the peak current and the n-base width and with the decrease of n-base doping concentration. In order to keep a low power dissipation, it is suggested that the n-base width should be smaller than 320μm when doping concentration is 1.0×10^14cm^-3 while the doping concentration should be higher than 5.8×10^13cm^-3 when n-base width is 270μm.

Opportunities and Challenges for the Development of China's Community Gardens

Since the 1970s,community gardens have played an important role in promoting the development of sustainable communities and improving urban environments in the United States. Despite the popularity of spontaneous urban farming activities in China,community gardens have not caught on as an ecologically and socially sustainable urban development strategy. Based on a comparison of community garden development in China and the U.S.,the authors of this article fi nd that the development of community gardens in China will require close collaboration between city planning officials,real estate agencies,urban citizens,and landscape architects.

Prediction Method of Vessel Maintenance Outlay Based on the BP Neural Network

With the development of technology, the performance of vessel equipment is improved, the structure is more complicated, the automation level is enhanced, the source needed by maintenance is increased and the outlay is rising day by day. For these questions, this paper analyzes the factors that affect the outlay of equipment maintenance, and describes the computational principle of the BP (back propagation) artificial neural network and its applications in the maintenance of naval ship and craft. Finally, a dynamic investment prediction model of outlay for the military equipment maintenance is designed. It is important for decreasing the entire life period outlay and drawing up the maintenance plan and programming to analyze the position and action of maintenance outlay in entire life period outlay.