bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterization of Tolerance Induction through Prenatal Marrow Transplantation: The Requirement for a Threshold Level of Chimerism to Establish Rather than Maintain Postnatal Skin Tolerance
Authors: Chen Jeng-Chang , Kuo Ming-Ling , Ou Liang-Shiou , Chang Pei-Yeh , Muench Marcus O. , Shen Chia-Rui , Chang Hsueh-Ling , Yu Hsiu-Yueh , Fu Ren-Huei
Published: December 2010

Hematopoietic chimerism resulting from prenatal marrow transplantation does not consistently result in allotolerance for unidentified causes. In a C57BL/6-into-FVB/N murine model, we transplanted T-cell-depleted adult marrow on gestational day 14 to elucidate the immunological significance of chimerism towards postnatal tolerance. Postnatally, chimerism was examined by flow cytometry, and tolerance by skin transplantation and mixed lymphocyte reaction. Regulatory T cells were quantified by FoxP3 expression. Peripheral chimerism linearly related to thymic chimerism, and predicted the degree of graft acceptance with levels >3% at skin placement, yielding consistent skin tolerance. Low- and high-level chimeras had lower intrathymic CD3highexpression than microchimeras or untransplanted mice. Regardless of the skin tolerance status in mixed chimeras, donor-specific alloreactivity by lymphocytes was suppressed but could be partially restored by exogenous interleukin-2. Recipients that lost peripheral chimerism did not accept donor skin unless prior donor skin had engrafted at sufficient chimerism levels, suggesting that complete tolerance can develop as a consequence of chimerism-related immunosuppression of host lymphocytes and the tolerogenic effects of donor skin. Thus, hematopoietic chimerism exerted immunomodulatory effects on the induction phase of allograft tolerance. Once established, skin tolerance did not fade away along with spontaneous regression of peripheral and tissue chimerism, as well as removal of engrafted donor skin. Neither did it break following in vivo depletion of increased regulatory T cells, and subcutaneous interleukin-2 injection beneath the engrafted donor skin. Those observations indicate that the maintenance of skin tolerance is multifaceted, neither solely dependent upon hematopoietic chimerism and engrafted donor skin nor on the effects of regulatory T cells or clonal anergy. We conclude that hematopoietic chimerism generated by in utero hematopoietic stem cell transplantation is critical to establish rather than maintain postnatal skin tolerance. Therefore, the diminution of hematopoietic chimerism below a threshold level does not nullify an existing tolerance state, but lessens the chance of enabling complete tolerance.
Efficacy of Periodontal Stem Cell Transplantation in the Treatment of Advanced Periodontitis
Authors: Park Joo-Young , Jeon Soung Hoo , Choung Pill-Hoon
Published: December 2010

Periodontitis is the most common cause for tooth loss in adults and advanced types affect 10–15% of adults worldwide. The attempts to save tooth and regenerate the periodontal apparatus including cementum, periodontal ligament, and alveolar bone reach to the dental tissue-derived stem cell therapy. Although there have been several periodontitis models suggested, the apical involvement of tooth root is especially challenging to be regenerated and dental stem cell therapy for the state has never been investigated. Three kinds of dental tissue-derived adult stem cells (aDSCs) were obtained from the extracted immature molars of beagle dogs ( n = 8), and ex vivo expanded periodontal ligament stem cells (PDLSCs), dental pulp stem cells (DPSCs), and periapical follicular stem cells (PAFSCs) were transplanted into the apical involvement defect. As for the lack of cementum-specific markers, anti-human cementum protein 1 (rhCEMP1) antibody was fabricated and the aDSCs and the regenerated tissues were immunostained with anti-CEMP1 antibody. Autologous PDLSCs showed the best regenerating capacity of periodontal ligament, alveolar bone, and cementum as well as peripheral nerve and blood vessel, which were evaluated by conventional and immune histology, 3D micro-CT, and clinical index. The rhCEMP1 was expressed strongest in PDLSCs and in the regenerated periodontal ligament space. We suggest here the PDLSCs as the most favorable candidate for the clinical application among the three dental stem cells and can be used for treatment of advanced periodontitis where tooth removal was indicated in the clinical cases.
Targeting Uncoupling Protein-2 Improves Islet Graft Function
Authors: Zhang Dong , Shen Miaoda , Mikita Allison , Zhang Wensheng , Liu Yun , Liu Quan , Dai Yifan , Zhang Chenyu , Zheng Shusen , Zheng Xin Xiao
Published: December 2010

Preserving and enhancing the primary function of transplanted islets is not only crucial for improving the outcome of the islet transplantation, but is also important for reducing the islet mass required to achieve insulin independence. Uncoupling protein 2 (UCP2) is a member of the uncoupling protein family, which is localized to the inner mitochondrial membrane and negatively regulates insulin secretion in the pancreatic β-cells. In this study, we assessed the importance of UCP2 in improving islet graft primary function by using UCP2 gene-knockout (UCP2-KO) mice in a syngeneic islet transplantation model. Islets were isolated from UCP2-KO or wild-type (WT) C57BL/6J mice. The effects of deficiency of UCP2 on islet transplantation and islet function were determined. Two hundred islets from UCP2-KO, but not from WT, donors were capable of completely restoring normoglycemia in 1 week in all syngeneic diabetic recipients. Islets harvested from UCP2-KO mice secreted onefold more insulin in GSIS assay than that from WT mice, and maintained normal GSIS after 72-h exposure to high glucose challenge. In addition, UCP2-KO islets expressed twohold higher Bcl-2 mRNA than that from WT islets, and were resistant to high glucose and proinflammatory cytokine induced death. Our study explored a potential mechanism that may explain the benefit of UCP2-KO islets in islet transplantation. Targeting UCP2 may provide a novel strategy to improve primary function of transplanted islets and reduce the number of islets required in transplantation.
Amniotic Membrane Application Reduces Liver Fibrosis in a Bile Duct Ligation Rat Model
Authors: Sant'anna Luciana B. , Cargnoni Anna , Ressel Lorenzo , Vanosi Graziella , Parolini Ornella
Published: December 2010

Biliary fibrosis and resultant cirrhosis are among the most common outcomes of chronic liver diseases. Currently, liver transplantation remains the only effective treatment. In seeking alternative therapeutic approaches, we focused on the potential use of the human amniotic membrane (AM). Indeed, AM has gained increasing importance for its antiscarring, anti-inflammatory, and wound-healing properties, as well as for the multipotent differentiation ability and immunomodulatory features of AM-derived cells. Intriguingly, we have recently demonstrated that placenta-derived cells reduce lung fibrosis in bleomycin-treated mice, and that AM patches reduce postischemic cardiac injury in rats. Hence, we have now investigated the effects of human AM on biliary fibrosis induced in rats through the bile duct ligation (BDL) procedure. A fragment of human AM was applied onto the liver surface after BDL and the effects on fibrosis establishment and progression were evaluated at different time points in comparison with fibrosis progression in control BDL rats. The degree of liver fibrosis was first assessed by the semiquantitative Knodell scoring system and, thereafter, by digital image morphometric analysis to quantify the area occupied by ductular reaction, activated myofibroblasts, and collagen deposition. We demonstrated a significant reduction in the severity of BDL-induced fibrosis in AM-treated rats. Indeed, while fibrosis progressed rapidly in control BDL rats, leading to cirrhosis within 6 weeks, AM-treated rats showed confined fibrosis at the portal/periportal area with no signs of cirrhosis, and a reduction in collagen deposition to about 50% of levels observed in control BDL rats. In addition, the AM was able to significantly slow the gradual progression of the ductular reaction and reduce, at all time points, the area occupied by activated myofibroblasts. These findings suggest that human AM, when applied as a patch onto the liver surface, might inhibit fibrosis progression in BDL-injured livers, and could protect against hepatic damage associated with fibrotic degeneration.
Neural Stem Cells Reduce Hippocampal Tau and Reelin Accumulation in Aged Ts65Dn down Syndrome Mice
Authors: Kern D. S. , Maclean K. N. , Jiang H. , Synder E. Y. , Sladek J. R. , Bjugstad K. B.
Published: December 2010

Tau accumulation, in the form of neurofibrillary tangles (NFT), is an early neuropathological characteristic of Alzheimer's disease (AD) and early onset AD frequently seen in Down syndrome (DS). We investigated the presence of tau accumulation in the brains of aging DS mice using the Ts65Dn mouse model. All aged mice appeared to have substantial clusters of extracellular granules that were positive for tau and reelin, but not for amyloid-β or APP. These clusters were found primarily in CA1 of the hippocampus. In addition, the aged trisomic DS mice had a significantly greater accumulation of extracellular tau/reelin granular deposits compared to disomic littermates. These granules were similar to those described by others who also found extracelluar proteinous granules in the brains of non-DS mice engineered to model aging and/or AD. When neural stem cells (NSC) were implanted unilaterally into the hippocampus of the Ts65Dn mice, the tau/reelin-positive granules were significantly reduced in both trisomic and disomic mice. Our findings indicate that changes in tau/reelin-positive granules could be used as an index for neuropathological assessment in aging DS and AD. Furthermore, changes in granule density could be used to test the efficacy of novel treatments, such as NSC implantation. Lastly, it is speculated that the unique abilities of NSC to migrate and express growth factors might be a contributing factor to reducing tau/reelin accumulation in aging DS and AD.
Human Amniotic Epithelial Cells Induce Localized Cell-Mediated Immune Privilege in Vitro: Implications for Pancreatic Islet Transplantation
Authors: Qureshi Khalid M. , Oliver Robert J. , Paget Michelle B. , Murray Hilary E. , Bailey Clifford J. , Downing Richard
Published: December 2010

Chronic systemic immunosuppression in cell replacement therapy restricts its clinical application. This study sought to explore the potential of cell-based immune modulation as an alternative to immunosuppressive drug therapy in the context of pancreatic islet transplantation. Human amniotic epithelial cells (AEC) possess innate anti-inflammatory and immunosuppressive properties that were utilized to create localized immune privilege in an in vitro islet cell culture system. Cellular constructs composed of human islets and AEC (islet/AEC) were bioengineered under defined rotational cell culture conditions. Insulin secretory capacity was validated by glucose challenge and immunomodulatory potential characterized using a peripheral blood lymphocyte (PBL) proliferation assay. Results were compared to control constructs composed of islets or AEC cultured alone. Studies employing AEC-conditioned medium examined the role of soluble factors, and fluorescence immunocytochemistry was used to identify putative mediators of the immunosuppressive response in isolated AEC monocultures. Sustained, physiologically appropriate insulin secretion was observed in both islets and islet/AEC constructs. Activation of resting PBL proliferation occurred on exposure to human islets alone but this response was significantly ( p < 0.05) attenuated by the presence of AEC and AEC-conditioned medium. Mitogen (phytohaemagglutinin, 5 μg/ml)-induced PBL proliferation was sustained on contact with isolated islets but abrogated by AEC, conditioned medium, and the islet/AEC constructs. Immunocytochemical analysis of AEC monocultures identified a subpopulation of cells that expressed the proapoptosis protein Fas ligand. This study demonstrates that human islet/AEC constructs exhibit localized immunosuppressive properties with no impairment of β-cell function. The data suggest that transplanted islets may benefit from the immune privilege status conferred on them as a consequence of their close proximity to human AEC. Such an approach may reduce the need for chronic systemic immunosuppression, thus making islet transplantation a more attractive treatment option for the management of insulin-dependent diabetes.
Cell Transplantation for Articular Cartilage Defects: Principles of Past, Present, and Future Practice
Authors: Jiang Yang Zi , Zhang Shu Fang , Qi Yi Ying , Wang Lin Lin , Ouyang Hong Wei
Published: December 2010

As articular cartilage has very limited self-repair capability, the repair and regeneration of damaged cartilage is a major challenge. This review aims to outline the past, present, and future of cell therapies for articular cartilage defect repair. Autologous chondrocyte implantation (ACI) has been used clinically for more than 20 years, and the short, medium, and long-term clinical outcomes of three generation of ACI are extensively overviewed. Also, strategies of clinical outcome evaluation, ACI limitations, and the comparison of ACI clinical outcomes with those of other surgical techniques are discussed. Moreover, mesenchymal stem cells and pluripotent stem cells for cartilage regeneration in vitro, in vivo, and in a few clinical studies are reviewed. This review not only comprehensively analyzes the ACI clinical data but also considers the findings from state-of-the-art stem cell research on cartilage repair from bench and bedside. The conclusion provides clues for the future development of strategies for cartilage regeneration.
Adult Hippocampal Neurogenesis: A Possible Way how Physical Exercise Counteracts Stress
Authors: Yau Suk-Yu , Lau Benson Wui-Man , So Kwok-Fai
Published: December 2010

It was considered that neurogenesis only occurred during the embryonic and developmental stage. This view has greatly changed since the discovery of adult neurogenesis in two brain regions: the hippocampus and the olfactory bulb. Recently, it is suggested that altered hippocampal neurogenesis is related to pathophysiology of mood disorders and mechanism of antidepressant treatments. Accumulating knowledge about the effects of physical exercise on brain function suggests a special role of adult hippocampal neurogenesis in cognitive and mental health, even though the functional significance of adult neurogenesis is still debated. The beneficial effects of running correlating with increased adult neurogenesis may provide a hint that newborn neurons may be involved, at least in part, in the counteractive mechanism of physical exercise on stress-related disorders, like depression. The present review provides an overview of recent findings to emphasize the possible involvement of hippocampal neurogenesis in mediating the beneficial effects of physical exercise on counteracting stress.
Human Mesenchymal Stem Cells from Chorionic Villi and Amniotic Fluid are not Susceptible to Transformation after Extensive in Vitro Expansion
Authors: Poloni Antonella , Maurizi Giulia , Babini Lucia , Serrani Federica , Berardinelli Eleonora , Mancini Stefania , Costantini Benedetta , Discepoli Giancarlo , Leoni Pietro
Published: December 2010

Mesenchymal stem cells (MSCs) are promising candidates for cell therapy and tissue engineering. Increasing evidence suggests that MSCs isolated from fetal tissues are more plastic and grow faster than adult MSCs. In this study, we characterized human mesenchymal progenitor cells from chorionic villi (CV) and amniotic fluid (AF) isolated during the first and second trimesters, respectively, and compared them with adult bone marrow-derived MSCs (BM). We evaluated 10 CV, 10 AF, and 6 BM samples expanded until the MSCs reached senescence. We used discarded cells from prenatal analyses for all the experiments. To evaluate the replicative stability of these cells, we studied the telomerase activity, hTERT gene transcription, and telomere length in these cells. Spontaneous chromosomal alterations were excluded by cytogenetic analysis. We studied the expression of c-myc and p53, tumor-associated genes, at different passage in culture and the capacity of these cells to grow in an anchorage-independent manner by using soft agar assay. We isolated homogeneous populations of spindle-shaped CV, AF, and BM cells expressing mesenchymal immunophenotypic markers throughout the period of expansion. CV cells achieved 14 ± 0.9 logs of expansion in 118 days and AF cells achieved 21 ± 0.9 logs in 118 days, while BM cells achieved 11 × 0.4 logs in 84 days. Despite their high proliferation capacity, fetal MSCs showed no telomerase activity, no hTERT and c-myc transcriptions, and maintained long, stable telomeres. A constant expression level of p53 and a normal karyotype were preserved throughout long-term expansion, suggesting the safety of fetal MSCs. In conclusion, our results indicate that fetal MSCs could be an alternative, more accessible resource for cell therapy and regenerative medicine.
Embryonic Stem Cell Transplantation into Seminiferous Tubules: A Model for the Study of Invasive Germ Cell Tumors of the Testis
Authors: Silván Unai , Díez-Torre Alejandro , Andrade Ricardo , Arluzea Jon , Silió Margarita , Aréchaga Juan
Published: December 2010

Over the last 15 years, cell transplantation into seminiferous tubules has become a valuable tool to study germinal cell biology and related matters. This is particularly so, because the blood–testis permeability barrier establishes a sealed compartment which protect against certain influences such as immunological rejection. In the light of the functional and genetic similarities between carcinoma in situ (CIS) of the testis and embryonic stem (ES) cells, our laboratory has developed a tumor assay to study cancer invasion processes in testicular germ cell tumors (TGCT) based on the transplantation of ES cells into the seminiferous tubules. Here, we describe this new tumor assay and provide additional information regarding the transplantation techniques used and their application for the study of TGCTs. Finally, we discuss the practical implications of our experimental approach and its potential application for the understanding of TGCT invasive processes and the development of new antineoplastic strategies.
Glucose Reduction Prevents Replicative Senescence and Increases Mitochondrial Respiration in Human Mesenchymal Stem Cells
Authors: Lo Ting , Ho Jennifer H. , Yang Muh-Hwa , Lee Oscar K.
Published: December 2010

The unique self-renewal and multilineage differentiation potential of mesenchymal stem cells (MSCs) make them a promising candidate for cell therapy applications. However, during in vitro expansion of MSCs, replicative senescence may occur and will compromise the quality of the expanded cells. Because calorie restriction has been shown to effectively extend the life span of various organisms, the purpose of this study is to investigate the effect of glucose reduction on MSCs and the coordinated changes in energy utilization. It was found that the frequency of cycling cells was significantly increased, while senescence markers such as β-galactosidase activities and p16INK4aexpression level were markedly reduced in MSCs under low-glucose culture condition. Quantitative real-time PCR analysis demonstrated the preserved trilineage differentiation potentials of MSCs after low-glucose treatment. Interestingly, the ability of osteogenic lineage commitment was improved, while the ability of adipogenic lineage commitment was delayed in MSCs after glucose reduction. In addition, we observed decreased lactate production, increased electron transport chain complexes expression, and increased oxygen consumption in MSCs after glucose reduction treatment. Increased antioxidant defensive responses were evidenced by increased antioxidant enzymes expression and decreased superoxide production after glucose reduction. Taken together, our findings suggest that MSCs utilize energy more efficiently under restricted glucose treatment and exhibit greater self-renewal and antisenescence abilities, while their differentiation potentials remain unaffected.
Autologous Transplantation of Amniotic Fluid-Derived Mesenchymal Stem Cells into Sheep Fetuses
Authors: Shaw S. W. Steven , Bollini Sveva , Nader Khalil Abi , Gastadello Annalisa , Mehta Vedanta , Filppi Elisa , Cananzi Mara , Gaspar H. Bobby , Qasim Waseem , De Coppi Paolo , David Anna L.
Published: December 2010

Long-term engraftment and phenotype correction has been difficult to achieve in humans after in utero stem cell transplantation mainly because of allogeneic rejection. Autologous cells could be obtained during gestation from the amniotic fluid with minimal risk for the fetus and the mother. Using a sheep model, we explored the possibility of using amniotic fluid mesenchymal stem cells (AFMSCs) for autologous in utero stem cell/gene therapy. We collected amniotic fluid (AF) under ultrasound-guided amniocentesis in early gestation pregnant sheep ( n = 9, 58 days of gestation, term = 145 days). AFMSCs were isolated and expanded in all sampled fetal sheep. Those cells were transduced using an HIV vector encoding enhanced green fluorescent protein (GFP) with 63.2% (range 38.3–96.2%) transduction efficiency rate. After expansion, transduced AFMSCs were injected into the peritoneal cavity of each donor fetal sheep at 76 days under ultrasound guidance. One ewe miscarried twin fetuses after amniocentesis. Intraperitoneal injection was successful in the remaining 7 fetal sheep giving a 78% survival for the full procedure. Tissues were sampled at postmortem examination 2 weeks later. PCR analysis detected GFP-positive cells in fetal tissues including liver, heart, placenta, membrane, umbilical cord, adrenal gland, and muscle. GFP protein was detected in these tissues by Western blotting and further confirmed by cytofluorimetric and immunofluorescence analyses. This is the first demonstration of autologous stem cell transplantation in the fetus using AFMSCs. Autologous cells derived from AF showed widespread organ migration and could offer an alternative way to ameliorate prenatal congenital disease.
Striatal Stimulation Nurtures Endogenous Neurogenesis and Angiogenesis in Chronic-Phase Ischemic Stroke Rats
Authors: Morimoto Takamasa , Yasuhara Takao , Kameda Masahiro , Baba Tanefumi , Kuramoto Satoshi , Kondo Akihiko , Takahashi Kazuya , Tajiri Naoki , Wang Feifei , Meng Jing , Ji Yuan Wen , Kadota Tomohito , Maruo Tomoko , Kinugasa Kazushi , Miyoshi Yasuyuki , Shingo Tetsuro , Borlongan Cesario V. , Date Isao
Published: December 2010

Deep brain stimulation (DBS) is used to treat a variety of neurological disorders including Parkinson's disease. In this study, we explored the effects of striatal stimulation (SS) in a rat model of chronic-phase ischemic stroke. The stimulation electrode was implanted into the ischemic penumbra at 1 month after middle cerebral artery occlusion (MCAO) and thereafter continuously delivered SS over a period of 1 week. Rats were evaluated behaviorally coupled with neuroradiological assessment of the infarct volumes using magnetic resonance imaging (MRI) at pre- and post-SS. The rats with SS showed significant behavioral recovery in the spontaneous activity and limb placement test compared to those without SS. MRI visualized that SS also significantly reduced the infarct volumes compared to that at pre-SS or without SS. Immunohistochemical analyses revealed a robust neurogenic response in rats that received SS characterized by a stream of proliferating cells from the subventricular zone migrating to and subsequently differentiating into neurons in the ischemic penumbra, which exhibited a significant GDNF upregulation. In tandem with this SS-mediated neurogenesis, enhanced angiogenesis was also recognized as revealed by a significant increase in VEGF levels in the penumbra. These results provide evidence that SS affords neurorestoration at the chronic phase of stroke by stimulating endogenous neurogenesis and angiogenesis.
Design and Development of Screw-Drive In-Pipe Robot
Authors: Deng Jia Ming , Shen Hui Ping , Xue Chang Yu , Liu Shan Shu , Wang Xin Xiang
Published: December 2010

The design and development of a screw-drive in-pipe robot is presented. The robot is composed of power-driving module, walking orientation module, universal joints, and accessories. The application of automatic spring structure on the robot improves its adaptability. The robot is able to move smoothly in the vertical, inclined, or horizontal pipelines, or even when the cross-section of the pipe is not strictly circular. The calculation formulae of robot walking speed and motor driving torque are derived in this paper. According to the geometries at the bend and the motion constraints, the robot turning capacity and turning condition are also analyzed. The vertical, bend, and other tests are performed on the experimental prototype, demonstrating that the screw-drive in-pipe robot provides sufficient tractive forces and good maneuverability and adaptability.
Study on Delta Parallel Mechanism Kinematics and Singularity Based on Inverse Solution
Authors: Chen Zhong Jie , Zhang Qui Ju , Hua Chun Jian
Published: December 2010

In this paper, the kinematic analysis on a 3-DOF Delta parallel mechanism was carried out and the relationship models between the end cell output motions and the master arms input parameters were established. The forward and inverse solutions to position, velocity and acceleration were deduced and then verified by simulation, the curves that gotten by calculation and simulation were smooth, and no mutations or jumps appeared. In the meantime, based on the kinematic analysis, the impact of Jacobian matrix on the manipulator singular configuration was discussed, and the maneuverability in the reachable space was obtain quantitatively, meanwhile, the value of cond(C(Jv)) was located in the acceptable range, which approached to the isotropic value, so, the theory basis for optimal design was provided. The methods and conclusions in this paper are helpful to the design and control of 3-DOF Delta parallel mechanism.
Simulation and Optimization Design on the Amplitude Changing Mechanism of Boom System of Five-Arm Concrete Pump Vehicle
Authors: Ling Zhi Yong , Fu Peng Fei
Published: December 2010

The 3D entity model for the amplitude changing mechanism of boom system of certain 48 meters concrete pump vehicle was established by means of Pro/E software, and then it was imported into ADAMS/VIEW to find out the maximum load carrying capacity of hydraulic cylinder under various working conditions. Under the environment of ADAMS/VIEW, parametric model of boom system was built. Utilizing the measure of design evaluation tools (DET) in ADAMS, optimization design of the amplitude changing mechanism of boom system was commendably achieved. This method evidently minimized the maximum load carrying capacity of hydraulic cylinder, and greatly improved the working performance of boom system.
Research on Copper Foil Post-Processor Tension Control System
Authors: Xing Wan , Jiang Yong
Published: December 2010

The copper foil post-processor is used to deal with the surface of copper, and the tension control is an important issue for the quality of the product.With reference to the process of copper foil post-treatment, this paper introduces the hardware and software design of its tension control system respectively and the result has fulfilled the tension control function very well.
Research on Calculation System Used in Positioning Error
Authors: Wu Yong Xiang
Published: December 2010

There are two types of positioning benchmark for number of workpiece in fixture: single positioning and aggregate surface positioning. This paper introduces the research and development on calculation system used in positioning error based on single positioning benchmark such as cylinder hole or external surface of cylinder and aggregate surface positioning benchmark such as one surface two holes or axis of shoulder shaft. It plays an important role in improving CAFD function and building the foundation for CAPP/CAFD integrated system.
Study on a Principle of Grinding Process of Face Gear
Authors: Li Xiao Zhen , Li Zheng Min Qing , Zhu Ru Peng
Published: December 2010

In order to process the hardened face-gear, and improve the surface’s accuracy, the grinding process of face gear is studied. According to the equation of tooth surface, the tooth surface is drawn by a series of space curve, the contact point’s trajectory and velocity at the processing of grinding are determined in three coordinate directions. The model of grinding machine is set up, and analyses the movement of relationship between tool and face-gear. The simple grinding wheel apply complex movement to grinding process the face-gear is successful.
A New Realization Method of Control System for Magnetic Bearing
Authors: Zhang Wen Yue , Ge Yan Jun , Yang Jun Yue
Published: December 2010

Aiming at the problems of complex circuit and parameter adjustment in traditional current type power amplifier of Magnetic Bearing (MB), a new realization method of control system based on DSP (Digital Signal Processor) is proposed. The difference with traditional power amplifier is that the current control loop is realized through software in DSP, so some advanced control strategies will be adopted easily, and the control parameters could be modified freely. Besides, the models established in MATLAB using common control strategy and advanced strategy are simulated separately, and the simulation results show the better effect can be obtained with the latter. Finally, the rotor of a 1-DOF MB prototype can be suspended within 0.01mm in the experiment, and the control strategy and parameters can be modified freely by software in DSP.
Development of the Online Detection Controlling System on Stagnant Force of Car Seat Slideway
Authors: Ma Ru Hong , Ge You Hua , Wang Fu Yuan
Published: December 2010

An automatic detection device was developed to measure the frictional resistance force between the tracks on the brackets of car seats. The device adopted the force sensor to measure the action force of the tracks on line. The industrial computer was responsible for processing the data, dynamically drawing the value curve of the meter, collecting the order from the SCM and sending the controlling signal to the SCM. The applications show that the measuring system has the good dynamic performance, high measuring accuracy and reliability.
Improved Design of Thermal Airflow Process for the Annular Cooler and Fluent Simulation
Authors: Zhang Xi Liang , Gao Wen Xiang , Chen Li Qiang , Xu Jun , Feng Ai Xin
Published: December 2010

Considering the current problems of low temperature of recovered gas, the direct gas emission of the fourth cooling zone in the operation of the annular cooler, thermal airflow process for the annular cooler is improved by analyzing the thermal airflow process and the structure of the annular cooler and using the principle of repeated convective heat transfer. Thus the above-mentioned problem can be solved. Simulation model of its thermal airflow process is established and the simulation results, obtained by using Fluent software, are as follows: the temperature of the gas in the first cooling zone entering the rotary kiln of the improved is about 110°C higher than that of the unimproved, the temperature of the gas in the second cooling zone entering the preheat zone I of the chain grate of the improved is about 150°C higher than that of the unimproved, and the temperature of the gas in the fourth cooling zone entering the downdraft drying zone of the chain grate of the improved is about 50°C higher than that of the unimproved. Pellet heat recovery efficiency is increased significantly.
Research on Energy Estimation Mechanism for Wireless Sensor Nodes
Authors: Yu Xin , Chen Zu Jue , Cai Xiao Lei
Published: December 2010

Energy is one of the most important parts of wireless sensor network design. Effective estimate the residual power of sensor nodes can be used to aid select the all-round and optimal schemes for applications and router protocols design, which can notably promote the survival period of wireless sensor networks. By software based real time energy estimation to scale the power consume of nodes can conciliate the deficiency of hardware. However, because node energy loss is nonlinear, so software based real time estimation inevitably not accurate. On the contrary, hardware based method scale residual energy in terms of reliability, efficiency and accuracy are relatively better.
The Application of CAN Bus in Monitoring and Controlling System for Combine Harvester
Authors: Chen Jin , Zheng Yue Lan , Li Yao Ming , Wei Xin Hua
Published: December 2010

With ARM processor as upper computer and MCU as lower computers, a monitoring and controlling system for combine harvester is constructed in this paper. CAN bus is used here to realize decentralized control and centralized management. By monitoring and controlling running status of lower computers and relevant parameters through upper computer, the unit can work under an optimum working condition. Therefore, the unit’s work efficiency will be increased, and the fault rate will be reduced. Experiment shows that, upper computer can communicate with lower computers reliably. The expected goal is realized.
The Analysis of Static and Dynamic Characteristics of Motorized High-Speed Spindle Based on Sensitivity Analysis of FEM Model
Authors: Yuan Song Mei , Lv Mao Bin , Liu Xue Hao
Published: December 2010

In order to estimate the static and dynamic characteristics of motorized high-speed spindle, the full parameterized FEM model of it is established and studied in the paper. After the FEM analysis of the spindle, the static stiffness, natural frequency and normal modes of vibration are obtained. Then, a design sensitivity analysis of some design parameters is conducted based on the finite element model to investigate their influence on the static stiffness and natural frequency of the spindle system. Through the sensitivity analysis, the optimal plan is proposed, the first natural frequency as the first objective function of optimization and the static stiffness as the second, which changes the objective function of multivariable into that of a single one. Therefore, it considerably increases the efficiency of optimization. The optimization leads to a noticeable improvement of static stiffness and first-mode natural frequency.
Study of Liquid Desiccant Air Conditioning System Combined with Cognitive Sensing Network
Authors: Chen Jing Zhu , Huang Jun , Lv Yan , Song Xue Hua
Published: December 2010

The Application of Liquid Desiccant Absorption Air Conditioning System Is Booming; Governments, Investors, Researchers, Manufacturers, Resellers and Customers Are All Focusing on the Concepts of Environment Protection and Energy Saving, it Can Utilize Low Cost Energy as Regeneration Heat Source, for Example Solar Energy, Industry Waste Heat, Ground Heat. the System Utilizes Intelligent Wireless Sensor Network to Control the Air Conditions’ Operation, Optimize its Performance. on the other Side, the System Gets Rid of Freon Refrigerant, Doesn’t Create Pollution, Solved the both Energy and Environment Issues Effectively. the Paper Analyzed the Characteristics of the New Air Conditioning System, Tabled a Proposal of Combining the New Air Conditioning System with Ubiquitous Sensor and Pervasive Computing Platform, Discussed its Feasibility, Supply a Theory behind the Design.
Design of Battery Online Weighing System Based on PID-Fuzzy Control
Authors: Yin Su Min , Gao Rui Qiang , Zhou Qing , Zhang Ping
Published: December 2010

According to the principle of manganese powder forming, a battery online weighing system with PLC-based PID-Fuzzy control algorithm was designed. In this paper, we focus on the need for a detailed description of hardware and software and matlab simulation of the system. The system uses touch screen for realization of human-machine interaction with high stability, and double closed-loop controls overcome the disadvantages of the traditional offline open-loop control, those greatly improve the efficiency and accuracy of manganese ring weighing.
Research of Novel Hybrid-Electromagnetic Actuator with Adjustable Rigidity and Damping
Authors: Wu Wei Guang , Ma Lv Zhong
Published: December 2010

A novel hybrid-electromagnetic actuator with the permanent magnet is designed, by which the operating component can realize the to-and-fro driving movement by changing the current direction of its control coil and it is more convenient to use for active vibration control. The electromagnetic force of the actuator is theoretically calculated by equivalent magnetic circuit and by the finite element respectively. Finally the characteristic of its rigidity and damping in an active vibration isolation system are analyzed, and it is indicated that they are not only related to its structure parameters，but also to the parameter of controller.
Structure Analysis and Improvement of Mining Explosion-Proof Control Switch Case Based on ANSYS
Authors: Chen Fei , Shao Zhi Hao , Li Jian Ming
Published: December 2010

In this paper, the finite element model of the mining explosion-proof control switch case was established by ANSYS software. The case was analyzed by the nonlinear method, the weak area was found. Then, the correctness of the model was validated by hydraulic pressure test. Finally, a reasonable improved scheme of the case's structure was obtained. This thesis provides scientific information for design and optimization of the mining explosion-proof control switch case.
The Design of the Small and Low-Power LED Display System Based on Infrared Serial Communication
Authors: Fei Ji You , Zhou Mo , Gao Kai , Ji En Xiang
Published: December 2010

This paper described a new system for small LED display, which was based on the computer and MCU master-slave structure. The focus of host computer design is the extraction of Chinese characters dot-matrix data and the transmission of information using infrared serial communication. The lower computer has already accomplished dynamic LED display design with LPC900 series single-chip and the hardware drive circuit of LED display. The LED display system possessed a high performance-price ratio, and could be widely used in automated instrumentation panel and sensor online shows. This system also gets other extraordinary characters like small size (45×80×3mm3), light weight, low (power) consumption, and simple operation and so on.
3-Axis NC Rough Tool-Path Generation from Discrete Data Points of Reliefs
Authors: Liu Wei , Zhou Lai Shui , An Lu Ling
Published: December 2010

This paper presents an algorithm through which 3-axis NC rough tool-paths can be directly generated from discrete data points. Based on Inverse Tool Offset (ITO) method, the algorithm generates direction-parallel (DP) tool paths for relief point clouds. The algorithm includes four steps: dividing data points into 3D cell grids; constructing inverse tool model and calculating the grids intersecting the surface of inverse tool; obtaining the grids containing cutter location points; calculating tool paths. The experiment results indicate that the algorithm of the rough tool paths is efficient.
Two-Dimensional Stability Analysis of Interrupted High-Speed Milling
Authors: Lin Zi Xiong , Huang Xiang , Akhtar Muhammad Masud
Published: December 2010

Significant research has been made regarding chatter stability of milling operations. This paper presents a 2 degree of freedom stability analysis model (2 DOF model) for interrupted cutting. The cutting process is divided into two parts namely “free vibration” and “forced vibration” considering the flexibility in x and y directions. Calculating the solutions of the two parts, a four-dimensional-single-variation discretization map is established and the eigenvalues of the Jacques Matrix are checked at the fixed point on the Floquet unit circle. The two Neimark-Sacker and flip bifurcations are evaluated. The research work shows that the up milling is more stable than the down milling under the same operating parameters. The comprison of the proposed 2 DOF model with Davies one degree of dimensional model (1 DOF Davieas model) has been made in the paper which shows that the area of stable region in the proposed model is greater than the stable region in the 1 DOF Davies model. In the last the results of the experiments support the proposed model has been verified by experimentation.
Countermeasures against the Noise of Ring-Plate-Type Cycloid Reducer
Authors: Liu Yan , Liu Wen , Yang Bing , Zhang Xiao Pai
Published: December 2010

Double crank ring-plate-type cycloid reducer reserves the merits of the traditional cycloid drive, such as more meshing teeth, small angle between radial force and tangential force, hard surface of cycloid gear and pin-tooth. However, the noise of the reducer becomes more and more serious with the increase of speed and load. The noise of the reducer under different work conditions is measured with the SQLabⅡ data acquisition recorder and the collected data are analyzed through Artemis software. Some measures including involute helical cylindrical gear, adding rubber bearing and thickening the cover plate are presented to reduce the noise.
Study on Characteristics of Inner Ring Laser Powder Feed Molten Pool of Thin Workpiece
Authors: Wu Shao Hua , Shi Shi Hong , Xiao Jun Yan , Fu Ge Yan
Published: December 2010

In order to obtain the characteristic parameters of molten pool and realize real-time control of laser power, a high-speed CCD is used to monitor the laser rapid forming process of thin-walled rotating hollow cone, which is based on the technology of "hollow beam, powder tube center, inside-beam powder feeding".Experiments show that: In the plateau stage, pool area changes in 0.25mm2-0.7mm2, laser power remains at about 1kw, formed parts achieves maximum height of 55mm.
Comparison Research on the Machinability of Hardened Steel when Dry Turning with Ceramic and CBN Cutting Tools
Authors: Tu Chun Juan , Guo Xu Hong , Wang Wei , Wang Chi Hong
Published: December 2010

Researching on dry turning hardened steel was to replace the grinding with turning, which would improve efficiency and reduce cost. The contrast experiments of turning hardened steel with ceramic and CBN cutting tools were carried out. The cutting forces of two tools with different cutting parameters were measured by Kistler cutting force acquisition system. The difference with two chips was observed by scanning electron microscope(SEM). The experimental equations of cutting forces were built up by the linear regression analysis method. The results indicated that the variation trend of cutting forces with ceramic and CBN cutting tools in same conditions was same. The thrust force was maximal, next was tangential force, axial force was minimum. The thrust force and tangential force of ceramic cutting tools were almost double compared with CBN cutting tools. The shapes of chips with ceramic and CBN cutting tools were saw-tooth, the rough slice layer with periodic flow was shown on outer surface and the friction mask was distributed well-proportioned on inner surface. The spacing of rough slice layer of chips with CBN cutting tools was more wide, the friction mask of chips with ceramic cutting tools was more clear.
Modeling and Analysis for Transmission and Conversion of Hollow Circular Laser
Authors: Li Chun Sheng , Shi Shi Hong , Sun Cheng Feng , Wang Yong Kang , Liu Xiao Dong
Published: December 2010

This paper presents a new method of laser focusing used in the process of direct laser fabrication. The hollow laser beam is achieved by transmission and conversion, which is studied by modeling and analysis in this paper. The defocus distance Z must be regulated in order to fabricate clad layers with good quality. The relationship between laser focal spot and the defocus distance was investigated. The focusing laser was solid when the absolute value of Z was equal to or smaller than while hollow on the other focal planes with different defocus distances, and the diameter of the minimum focusing spot is .
Intelligent Fuzzy Controller Design and Simulation for Vehicle Speed Control
Authors: Li Jie Hui , Chen Chang Jun , Guo Lin Shan , Yan Bing Cheng
Published: December 2010

Through the study on fuzzy control in the vehicle speed control, the intelligent fuzzy controller with intelligent integral and differential is proposed. In this paper, we take diesel vehicle control system as an example, and the vehicle speed control system’s simulation has been completed. Simulation results show that the intelligent fuzzy controller could adapt to the model whose parameters are non-linear, time-varying, and this controller can also effectively inhibit the environmental interference, so the system with intelligent fuzzy controller has strong robustness, good reliability and higher control precision.
Elastic-Plastic Impact Loads of Steel Spheres Impacting on Planes
Authors: Liu Yu , Du Chang Long , Zhang Jia Jia , Jiang Hao
Published: December 2010

The impact between spheres and planes was a fundamental problem in the objects impacts. The impact loads were investigated for the different materials spheres impacting on the different materials planes in this paper. The results of the impact between two elastic materials were consistent with the Hertz results, which indicated that the finite element model was accurate and reliable. The simulation results showed that the impact loads would decrease if there were plastic deformations during the impact. For the same material properties of the plane and the sphere, the impact loads of the plane were higher than ones of the sphere. In other words, the impact between the same materials made the plane prone to fail. If the material properties of the plane and the sphere were different, the impact loads and deformations were depended on the ratio of the contact stress and the yield limit. The material in elastic stage had the lower impact loads compared with one in plastic stage. The material with plastic deformations would keep some residual stress and offset after the contact.
Experiment Study of Influence on Laser Beam Quality Induced by Thermal Lens Effect and Depolarization Effect
Authors: Ye Xia , Yao Hong Bing , Tong Yan Qun , Zhang Yong Kang , Cao Ruo Xi , Wang Xiang , Gao Yong Feng , Xu Xiao Fang
Published: December 2010

For high power and repetitive Nd:Glass laser, there would appear serious thermal effect due to the significantly-enhanced pumping optical power density in laser rod, which would induce thermal double refraction, phase distortion, thermal focusing, thermal depolarization, etc. Thus, the laser output power and beam quality would be influenced severely. Influence of thermal lens effect and depolarization effect caused by thermal stress double refraction on laser beam were studied in this paper for high power and repetitive laser. In the experiment of thermal lens effect, change of the laser spot by thermal lens effect was recorded after a TEM00 He-Ne laser beam passing through the Nd:Glass rod pumped by Xe lamp, and the corresponding optical compensator was applied to eliminate the thermal lens effect to improve the beam quality. Configuration of polarizer was designed in our experiment to research the depolarization effect caused by thermal stress double refraction. First, emergent light distribution and loss factor caused by double refraction was calculated according to the theoretical model. Then the exiting cone-shaped polarized light intensity distribution was obtained through the experiment. It could be obtained from the experiments that thermal lens effect and depolarization effect caused by thermal double refraction would reduce the output laser beam quality to varied extents. As the number of laser pulses increased, thermal effects began to emerge and the output laser energy apparently decreased; when the thermal effects steadied, the output energy would be tending towards stability.