A 4th-Order Wideband Sigma Delta Modulator Using Linear System Theory Technique

Ming-yuan Ren,Yong-sheng Zhang,Wei-kun Wu,Zhen-xi Bao,Zi-wei Zhao,Chao Li,Hong-guo Zhang 보안공학연구지원센터 2016 International Journal of Signal Processing, Image Vol.9 No.1

A 4th-Order Wideband Sigma Delta modulator structure is proposed in this paper, which uses linear system theory technique. There are many implementation techniques to improve the performance of Sigma Delta ADCs, such as noise coupling, differential sampling and dynamic elements matching. An extra loop delay is needed to be added in the system. This paper explains how to make the modulator stable with the addition of feed-forward and feed-back branches which are used to compensate the extra loop delay. Next, we restore the signal and noise transfer functions. A 4th-Order Wideband delta-sigma modulator have been designed and simulated to verify the method.

A Novel Hidden Markov model for Speech Recognition Modeling Various Statistical Distribution of Speech Featurs Space

Li Ming,YU Tiecheng,WEN Yuan,WANG Zhiyu,HOU Zhen 한국어정보학회 2002 한국어정보학 Vol.7ㆍ8 No.-

Optimization of algal lipid extraction by mixture of ethyl acetate and ethanol via response surface methodology for biodiesel production

Zhong-Ming Wang,Weidong Lu,Md Asraful Alam,Ying Pan,William Junior Nock,Zhen-Hong Yuan 한국화학공학회 2016 Korean Journal of Chemical Engineering Vol.33 No.9

The effects of extraction time, extraction temperature, solvent to biomass ratio and solvent composition on lipid yield from lyophilized Chlorococcum sp. biomass using a mixture of ethyl acetate and ethanol (EAE), a new proposed solvent, were studied. Subsequently, the process conditions of extraction by EAE were optimized using Box- Behnken design (BBD). The results revealed that the extraction temperature had the greatest effect on lipid extraction efficiency, followed by volume ratio of ethyl acetate to ethanol (EA/E) and extraction time. The largest lipid extraction yield of 15.74% was obtained under the following extraction conditions: 40mL solvents per gram of biomass for 270 min with gentle stirring at 80 oC by EAE with an EA/E of 1.0. Furthermore, palmitic acid, stearic acid, oleic acid, and linoleic acid were the most abundant fatty acids in the lipids extracted, indicating the great potential of the proposed lipid extraction procedure for microalgae-based biodiesel production.

Flux Sliding-mode Observer Design for Sensorless Control of Dual Three-phase Interior Permanent Magnet Synchronous Motor

Jian-Qing Shen,Lei Yuan,Ming-Liang Chen,Zhen Xie 대한전기학회 2014 Journal of Electrical Engineering & Technology Vol.9 No.5

A novel equivalent flux sliding-mode observer (SMO) is proposed for dual three-phase interior permanent magnet synchronous motor (DT-IPMSM) drive system in this paper. The DTIPMSM has two sets of Y-connected stator three-phase windings spatially shifted by 30 electrical degrees. In this method, the sensorless drive system employs a flux SMO with soft phase-locked loop method for rotor speed and position estimation, not only are low-pass filter and phase compensation module eliminated, but also estimation accuracy is improved. Meanwhile, to get the regulator parameters of current control, the inner current loop is realized using a decoupling and diagonal internal model control algorithm. Experiment results of 2MW-level DT-IPMSM drives system show that the proposed method has good dynamic and static performances.

Optimization of biodiesel production from trap grease via acid catalysis

Jin-Suk Lee,Zhong-Ming Wang,Ji-Yeon Park,Chuang-Zhi Wu,Zhen-Hong Yuan 한국화학공학회 2008 Korean Journal of Chemical Engineering Vol.25 No.4

As a kind of waste collected from restaurants, trap grease is a chemically challenging feedstock for biodiesel production for its high free fatty acid (FFA) content. A central composite design was used to evaluate the effect of methanol quantity, acid concentration and reaction time on the synthesis of biodiesel from the trap grease with 50% free fatty acid, while the reaction temperature was selected at 95 oC. Using response surface methodology, a quadratic polynomial equation was obtained for ester content by multiple regression analysis. Verification experiments confirmed the validity of the predicted model. To achieve the highest ester content of crude biodiesel (89.67%), the critical values of the three variables were 35.00 (methanol-to-oil molar ratio), 11.27 wt% (catalyst concentration based on trap grease) and 4.59 h (reaction time). The crude biodiesel could be purified by a second distillation to meet the requirement of biodiesel specification of Korea.

Flux Sliding-mode Observer Design for Sensorless Control of Dual Three-phase Interior Permanent Magnet Synchronous Motor

Shen, Jian-Qing,Yuan, Lei,Chen, Ming-Liang,Xie, Zhen The Korean Institute of Electrical Engineers 2014 Journal of Electrical Engineering & Technology Vol.9 No.5

A novel equivalent flux sliding-mode observer (SMO) is proposed for dual three-phase interior permanent magnet synchronous motor (DT-IPMSM) drive system in this paper. The DT-IPMSM has two sets of Y-connected stator three-phase windings spatially shifted by 30 electrical degrees. In this method, the sensorless drive system employs a flux SMO with soft phase-locked loop method for rotor speed and position estimation, not only are low-pass filter and phase compensation module eliminated, but also estimation accuracy is improved. Meanwhile, to get the regulator parameters of current control, the inner current loop is realized using a decoupling and diagonal internal model control algorithm. Experiment results of 2MW-level DT-IPMSM drives system show that the proposed method has good dynamic and static performances.

Phytoestrogen Intake and Risk of Ovarian Cancer: a Meta-Analysis of 10 Observational Studies

Qu, Xin-Lan,Fang, Yuan,Zhang, Ming,Zhang, Yuan-Zhen Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.21

Background: Epidemiology studies have shown an inconclusive relationship between phytoestrogen intake and ovarian cancer risk and there have been no relevant meta-analyses directly regarding this topic. The purpose of the present meta-analysis was therefore to investigate any association between phytoestrogen intake and ovarian cancer in detail. Materials and Methods: We conducted a search of PubMed, EMBASE, EBSCO, the Cochrane Library, CNKI and Chinese Biomedical Database (up to April 2014) using common keywords for studies that focused on phytoestrogen and ovarian cancer risk. Study-specific risk estimates (RRs) were pooled using fixed effect or random-effect models. Results: Ten epidemiologic studies were finally included in the meta-analysis. The total results indicated higher phytoestrogen intake was associated with a reduced ovarian cancer risk (RR, 0.70; 95%CI: 0.56-0.87). The association was similar in sensitivity analysis. Meta regression analysis demonstrated sources and possibly types and regions as heterogeneous factors. Subgroup analysis of types, sources and regions showed that isoflavones (RR: 0.63; 95%CI: 0.46, 0.86), soy foods (RR: 0.51; 95%CI: 0.39, 0.68) and an Asian diet (RR: 0.48; 95%CI: 0.37, 0.63) intake could reduce the incidence of ovarian cancer. Conclusions: Our findings show possible protection by phytoestrogens against ovarian cancer. We emphasize specific phytoestrogens from soy foods, but not all could reduce the risk. The habit of plentiful phytoestrogen intake by Asians is worthy to recommendation. However, we still need additional larger well designed observational studies to fully characterize underlying associations.

A Genetic Variant in MiR-146a Modifies Digestive System Cancer Risk: a Meta-analysis

Li, Ying-Jun,Zhang, Zhen-Yu,Mao, Ying-Ying,Jin, Ming-Juan,Jing, Fang-Yuan,Ye, Zhen-Hua,Chen, Kun Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.1

MicroRNAs (miRNAs) negatively regulate gene expression and act as tumor suppressors or oncogenes in oncogenesis. The association between a single nucleotide polymorphism (SNP) in miR-146a rs2910164 and susceptibility to digestive system cancers was inconsistent in previous studies. In this study, we conducted a literature search of PubMed to identify all relevant studies published before August 31, 2013. A total of 21 independent case-control studies were included in this updated meta-analysis with 9,558 cases and 10,614 controls. We found that the miR-146a rs2910164 polymorphism was significantly associated with decreased risk of digestive system cancers in an allele model (OR=0.90, 95%CI 0.87-0.94), homozygote model (OR=0.84, 95%CI 0.77-0.91), dominant model (OR=0.90, 95%CI 0.84-0.96), and recessive model (OR=0.85, 95%CI 0.79-0.91), while in a heterozygous model (OR = 0.99, 95% CI 0.89-1.11) the association showed marginal significance. Subgroup analysis by cancer site revealed decreased risk in colorectal cancer above allele model (OR=0.90, 95%CI 0.83-0.97) and homozygote model (OR=0.85, 95%CI 0.72-1.00). Similarly, decreased cancer risk was observed when compared with allele model (OR=0.87, 95%CI 0.81-0.93) and recessive model (OR=0.81, 95%CI 0.72-0.90) in gastric cancer. When stratified by ethnicity, genotyping methods and quality score, decreased cancer risks were also observed. This current meta-analysis indicated that miR-146a rs2910164 polymorphism may decrease the susceptibility to digestive system cancers, especially in Asian populations.

The Site-Directed A184S Mutation in the HTH Domain of the Global Regulator IrrE Enhances Deinococcus radiodurans R1 Tolerance to UV Radiation and MMC Shock

( Chen Zhang ),( Zhengfu Zhou ),( Wei Zhang ),( Zhen Chen ),( Yuan Song ),( Wei Lu ),( Min Lin ),( Ming Chen ) 한국미생물 · 생명공학회 2015 Journal of microbiology and biotechnology Vol.25 No.12

IrrE is a highly conserved global regulator in the Deinococcus genus and contributes to survival from high doses of UV radiation, ionizing radiation, and desiccation. Drad-IrrE and Dgob-IrrE from Deinococcus radiodurans and Deinococcus gobiensis I-0 each share 66% sequence identity. However, Dgob-IrrE showed a stronger protection phenotype against UV radiation than Drad-IrrE in the D. radiodurans irrE-deletion mutant (ΔirrE), which may be due to amino acid residues differences around the DNA-binding HTH domain. Site-directed mutagenesis was used to generate a Drad-IrrE A184S single mutant, which has been characterized and compared with the ΔirrE mutant complemented strain with Drad-irrE, designated ΔirrE-E. The effects of the A184S mutation following UV radiation and mitomycin C (MMC) shock were determined. The A184S mutant displayed significantly increased resistance to UV radiation and MMC shock. The corresponding A184 site in Dgob-IrrE was inversely mutated, generating the S131A mutant, which exhibited a loss of resistance against UV radiation, MMC shock, and desiccation. qPCR analysis revealed that critical genes in the DNA repair system, such as recA, pprA, uvrA, and ddrB, were remarkably induced after UV radiation and MMC shock in the ΔirrE-IE and A184S mutants. These data suggested that A184S improves the ability against UV radiation and MMC shock, providing new insights into the modification of IrrE. We speculated that the serine residue may determine the efficiency of DNA binding, leading to the increased expression of IrrE-dependent genes important for protection against DNA damage.

Design and Analysis of an Active Balancing Mechanism for a Vertical Axis Washing Machine

Hai-Wei Chen,Xun-Ting Yuan,Zhen Sun,Qiu-Qi Mou,Ming Xiong,Wei-Hua Wang 한국정밀공학회 2022 International Journal of Precision Engineering and Vol.23 No.7

In recent years, active balancing of washing machines has drawn much attention from manufactures. This paper proposes a novel active balancing mechanism for vibration suppression of a vertical axis washing machine which employs water for counteracting the unbalanced laundry. At first, a novel structure with two balancing planes sharing only one set of nozzles for injecting water is designed and the balancing capability of the structure is analyzed. Then, a dynamic model of the active balancing system is constructed. Vibration characteristics of the system including changes of the vibration amplitude and phase angle under different influences are studied. After that, a strategy for identifying the imbalance is proposed and an active control method is designed. At last, a washing machine armed with the active mechanism is manufactured. Both a fixed eccentric block and a pile of randomly distributed laundry are used to test the balancing effect. The results show that lateral vibrations of the washer can be greatly reduced by the active mechanism. Due to the simplicity of the structure and the satisfactory balancing effect, the mechanism proposed has a big potential to be employed in future washing machines.