Browsing by Author "Hsu, BM"

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Analysis for Giardia cysts and Cryptosporidium oocysts in water samples from small water systems in Taiwan
(2001-02-01)
Hsu, BM
;
Huang, CP
;
Hsu, CLL
;
環境工程研究所
;
Institute of Environmental Engineering
Giardia and Cryptosporidium have emerged as waterborne pathogens of concern. Twenty-six water samples were collected from small water systems in Taiwan and checked for the occurrence of both parasites. Water quality parameters and characteristics of the sampling sites were also recorded. The frequencies of occurrence for Giardia and Cryptosporidium were 46.2% for each; and their mean concentrations were 79.5 cysts/100 1 and 22.1 oocysts/100 1, respectively. The concentrations of oocysts and heterotrophic bacteria exhibited the highest correlation and followed the concentrations of the two protozoa. The water samples from sites with filtration devices had a lower oocyst concentration than those from sites without filtration devices, while no significant difference was found for cysts. The level of each parasite had no direct relationship with altitude. The cyst concentrations increased proportionally with the consumer population using the water systems. Risk assessment of the parasitic infections suggests that setting up disinfection devices in the small water systems would be needed.
C-pm MPPAC for manufacturing quality control applied to precision voltage reference process
(2004-05-01)
Pearn, WL
;
Shu, MH
;
Hsu, BM
;
工業工程與管理學系
;
Department of Industrial Engineering and Management
A multiprocess performance analysis chart (MPPAC), based on the process capability index C-pm, called C-pm MPPAC, is developed to analyse the manufacturing quality of a group of processes in a multiple process environment. The C-pm MPPAC conveys critical information about multiple processes regarding the departure of the process and process variability on one single chart. Existing research on MPPAC has been restricted to obtaining quality information from one single sample of each process, ignoring sampling errors. The information provided from the existing MPPAC chart, therefore, is unreliable and misleading, resulting in incorrect decisions. In this paper, the natural estimator of C(pm)is considered based on multiple samples. Based on the natural estimator of C-pm, sampling errors are considered by providing an explicit formula with Matlab to obtain the estimation accuracy of the C-pm. The sampling accuracy of C(pm)is tablulated for sample size determination so that engineers/practitioners can use it for in-plant applications. An example of multiple PVR processes is presented to illustrate the applicability of C-pm MPPAC for manufacturing quality control.
C-pm MPPAC for manufacturing quality control applied to the precision voltage reference process
(2004-07-01)
Pearn, WL
;
Shu, MH
;
Hsu, BM
;
工業工程與管理學系
;
Department of Industrial Engineering and Management
The multiprocess performance analysis chart (MPPAC) based on the process capability index C-pm, called C-pm MPPAC, is developed for analysing the manufacturing quality of a group of processes in a multiple process environment. The C-pm MPPAC conveys critical information of multiple processes regarding the departure of the process and process variability from one single chart. Existing research works on MPPAC are restricted to obtaining quality information from one single sample of each process ignoring sampling errors. The information provided from existing MPPAC charts, therefore, is unreliable and misleading and results in incorrect decisions. In this paper, we consider the natural estimator of C-pm based on multiple samples. Based on the natural estimator of C-pm, we consider the sampling errors by providing an explicit formula with the Matlab program to obtain the estimation accuracy of the C-pm. We tabulate the sampling accuracy of C-pm for sample size determination so that the engineers/practitioners can use it for their in-plant applications. An example of multiple precision voltage reference (PVR) processes is presented to illustrate the applicability of C-pm MPPAC for manufacturing quality control.
Evaluation of immunomagnetic separation method for detection of Giardia for different reaction times and reaction volumes
(2001-06-01)
Hsu, BM
;
Huang, CP
;
Lai, YC
;
Tai, HS
;
Chung, YC
Immunomagnetic separation (IMS) has been specified as a standard method for the measurement of Giardia. In this study, Dynal IMS was evaluated on the basis of recovery efficiencies of Giardia cysts for various IMS operational conditions. The average recoveries for Giardia in deionized, treated and raw water samples were 82.6 +/- 12.2% (n = 6), 75.6 +/- 15.2% (n=3), and 70.6 +/- 18.2% (n = 3), respectively. Significant changes in recovery were observed by altering the debris ratio and the debris components of water samples. Changing the reaction volume within the same vessel had no significant effect on cyst recovery efficiencies. However, prolonging the reaction time did increase recovery efficiencies.
Evaluation of two concentration methods for detecting Giardia and Cryptosporidium in water
(2001-02-01)
Hsu, BM
;
Huang, CP
;
Hsu, YF
;
Jiang, GY
;
Hsu, CLL
The cartridge filtration method and membrane filtration method based on the fluorescent antibody procedure were evaluated for their recovery efficiencies and detection limits of Giardia and Cryptosporidium. We assessed the performances of the two concentration methods for water samples collected from Taiwan water treatment plants. The membrane filtration method was characterized by higher recovery rate and detection limit comparing with the cartridge filtration method. The occurrences of both parasites, and the relationships of parasite concentrations with indicator microorganisms show inconsistency between the two methods. It was discovered that water turbidity reduced the recovery efficiencies, and raised the detection limits for both parasites regardless of the method used. (C) 2000 Elsevier Science Ltd. All rights reserved.
Examination of Giardia and Cryptosporidium in water samples and fecal specimens in Taiwan
(2000)
Hsu, BM
;
Huang, C
;
Hsu, YF
;
Hsu, CLL
;
環境工程研究所
Giardia and Cryptosporidium have emerged as waterborne pathogens of concern over the past few decades. Twenty-nine source water samples were collected from water treatment facilities and checked for the occurrence of Giardia and Cryptosporidium along with some water quality parameters. These facilities include ten large-scale treatment plants near major metropolitan areas, and eight simple facilities in small and secluded communities. The indirect immunofluorescence assay (IFA) was used for the detection of cysts and oocysts in water samples. In addition, fecal specimens were collected from watersheds providing source water for the treatment plants, and the presence of Giardia and Cryptosporidium was detected with the enzyme-linked immunosorbent assay (EIA). The mean concentrations of protozoa in large-scale plants were 66.8 cysts/100 litres and 89.2 oocysts/100 litres, while simple facilities contained 1.27 cysts/100 litres and 0.28 oocysts/100 litres, respectively. The concentrations of these two parasites exhibit the highest correlation with turbidity than any other water quality parameters. Among the 101 fecal specimens, eleven were positive for Giardia and 22 were positive for Cryptosporidium. It was also found that the occurrence of these two pathogens in the source water was directly linked to the surrounding farming activities, suggesting that farming activities should be kept at a certain distance from the watersheds.
Filtration behaviors of Giardia and Cryptosporidium - Ionic strength and pH effects
(2001-11-01)
Hsu, BM
;
Huang, CP
;
Pan, JR
;
環境工程研究所
;
Institute of Environmental Engineering
The laboratory-scale filtration tests of Giardia cysts and Cryptosporidium oocysts in both 2 mm-Phi glass beads and 2 mm-Phi polystyrene beads filters were conducted to investigate their filtration behaviors. The protozoan parasites were used as target particles. while the chemical system altered by changing the electrolyte concentration and pH, The results significantly indicate that ionic strength have a positive effect on the removal efficiencies for Giardia cysts and Cryptosporidium oocysts. The removal efficiency of two filters for Giardia cysts slightly decreased from pH 2.4 to 8.7 and decreased significantly in pH as pH up to 8.7, while that for Cryptosporidium slightly rippled beyond pH 8.7, and with the decrease in pH up to pH 8.7. The experimental collision efficiencies from the interactions between colloids and the filter media were calculated with a semi-empirical approach of the single sphere model and clean-bed filtration theory. The results also indicated that experimental collision efficiencies for (oo)cysts corresponded to the (oo)cysts removal efficiencies in all trials, and oocysts exhibits higher collision efficiencies than cysts. (C) 2001 Elsevier Science Ltd. All rights reserved.
Hydrogen sulfide removal by immobilized autotrophic and heterotrophic bacteria in the bioreactors
(1996-08-01)
Huang, CP
;
Chung, YC
;
Hsu, BM
;
交大名義發表
;
環境工程研究所
Autotrophic Thiobacillus sp. CH11 and heterotrophic Pseudomonas putida CH11 were isolated from piggery waste water. Extensive tests, including removal action, removal efficiency, removal capacity, and adaptability to perturbed conditions were conducted on autotrophic and heterotrophic biofilters. The results clearly demonstrate the application potential of autotrophic and heterotrophic biofilters for the continuous H2S removal under different perturbed conditions.
Influence of ionic strength and pH on hydrophobicity and zeta potential of Giardia and Cryptosporidium
(2002-03-05)
Hsu, BM
;
Huang, CP
;
環境工程研究所
;
Institute of Environmental Engineering
Surface charge and hydrophobicity of microorganisms are involved in interfacial interaction of cells, such as flocculation and adhesion. The calculated zeta potentials of Giardia cysts and Cryptosporidium oocysts in waters at neutral pH were on average - 17 and - 38 mV, respectively. The isoelectric points of cysts and oocysts were estimated as pH 2.2 and pH 3.3, respectively. The hydrophobicities of cysts and oocysts, obtained from the microbial adherence to hydrocarbons (MATH) test, were determined by initial removal rate. Although the initial removal rates of oocysts were larger than those of cysts in all trials, both demonstrated marked hydrophobicity. The hydrophobicities were significantly increased with decreasing pH for both protozoa. (C) 2002 Elsevier Science B.V. All rights reserved.
Lower confidence bounds for C-PU and C-PL based on multiple samples with application to production yield assurance
(2004-06-15)
Pearn, WL
;
Shu, MH
;
Hsu, BM
;
工業工程與管理學系
;
Department of Industrial Engineering and Management
For stably normal processes with one-sided specification limits, capability indices C-PU and C-PL have been used to provide numerical measures on production yield assurance. Statistical properties of the estimators of C-PU and C-PL have been investigated extensively for cases with a single sample. It is shown that for multiple samples, the uniformly minimum-variance unbiased estimators of C-PU and C-PL are consistent and asymptotically efficient. Based on the uniformly minimum-variance unbiased estimators, an algorithm is developed with an efficient program using a direct search method to compute the lower confidence bounds for C-PU and C-PL. The lower confidence bounds convey critical information to the minimum capability of a process, providing a necessary yield assurance of production. The lower confidence bounds are tabulated for some commonly used capability requirement so that engineers/practitioners can use them for their in-plant applications. An example of a high-speed buffer amplifier is presented to illustrate the practicality of the approach to data collected from the factories for production yield assurance.
Monitoring manufacturing quality for multiple Li-BPIC processes based on capability index C-pmk
(2005-06-15)
Pearn, WL
;
Shu, MH
;
Hsu, BM
;
工業工程與管理學系
;
Department of Industrial Engineering and Management
The multi-process performance analysis chart (MPPAC) based on process capability indices has been developed to analyse the manufacturing performance for multiple processes, which conveys critical information regarding the departure of the process mean from the target value, process variability, capability levels, which provides a guideline of directions for capability improvement. Existing MPPAC researches have plotted the sample estimates of the process indices on the chart. Conclusions were then made on whether processes meet the capability requirement and directions need to be taken for further quality improvement. Such an approach is highly unreliable since the sample point estimate is a random variable with no assessment of the sampling errors. Further, existing MPPAC researches only considered one single sample. Current quality control practice is to estimate process capability using multiple groups of control chart samples rather than one single sample. In this paper, we propose the C-pmk MPPAC combining the accuracy index C-a to access the performance of multiple manufacturing processes. Distributions of the estimated C-pmk and C-a are derived based on multiple control chart samples, and accurate lower confidence bounds are calculated. The lower confidence bounds of the estimated Cpmk and Ca are then employed to the MPPAC to provide reliable capability grouping for those multiple processes. A real-world example is presented to illustrate the applicability of the proposed MPPAC.
Occurrence of Giardia and Cryptosporidium in the Kau-Ping River and its watershed in southern Taiwan
(1999-08-01)
Hsu, BM
;
Huang, CP
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Hsu, CLL
;
Hsu, YF
;
Yeh, JH
Giardia and Cryptosporidium are important waterborne parasites. Thirteen water samples and 32 fecal specimens were collected from the Kau-Ping River and its watershed to test for Giardia cysts and Cryptosporidium oocysts. The detection methods are immunofluorescence assay and enzyme-linked immunosorbent assay for water samples and fecal specimens, respectively. Seven out of eight samples collected from raw water samples showed the presence of cysts, while six out of eight raw water samples contained oocysts. Cryptosporidium was present in 40% of the treated water, while Giardia occurred in all of them. Four out of 32 fecal specimens, collected from the hog farming region, tested positive for Giardia, and seven specimens tested positive for Cryptosporidium. Giardia was related only to Cryptosporidium but not to the others. (C) 1999 Elsevier Science Ltd. Ali rights reserved.
Performances of the immunomagnetic separation method for Cryptosporidium in water under various operation conditions
(2001-11-01)
Hsu, BM
;
Huang, CP
;
環境工程研究所
;
Institute of Environmental Engineering
Immunomagnetic separation (IMS) has been specified as a standard method for the measurement of Cryptosporidium in some countries. In this study, the IMS method was evaluated on the basis of the recovery efficiencies of Cryptosporidium oocysts at various IMS operation conditions. The average recovery for different Cryptosporidium concentrations in deionized water was 82.6 +/- 18.2% (n = 52), No significant change in recovery was observed by altering the debris ratio of the water samples. The efficiency was increased by prolonging the reaction time, and by increasing the amount of immunomagnetic beads. The recoveries of oocysts seeded in an Eppendorf with a small reaction volume were similar to those seeded in glass tubes with 10 times the reaction volume. The recovery efficiency of oocysts was reduced significantly when the reaction buffer was replaced by PBS. In conclusion, this method has good reproducibility and high recovery.
Recovery of Giardia and Cryptosporidium from water by various concentration, elution, and purification techniques
(2000-09-01)
Hsu, BM
;
Huang, C
;
環境工程研究所
;
Institute of Environmental Engineering
The performances of different concentration and elution techniques, as well as two purification methods, were evaluated in terms of their recovery efficiencies of Giardia cysts and Cryptosporidium oocysts from seeded deionized water, treated water, and raw water samples. Out of the three concentration techniques, the Envirochek capsule filtration followed by the membrane filtration consistently gave the highest recovery efficiencies for both protozoan parasites. Although the cartridge filtration is the most suitable technique for handling large quantities of water, it also brought the greatest loss of protozoan parasites. For elution and centrifugation, both the membrane filter with hand-kneading and Envirochek capsule with wrist-action shaking attained higher recovery efficiencies for cysts and oocysts. Immunomagnetic separation (IMS), the purification procedure in Method 1623, had a much higher recovery efficiency for both Giardia and Cryptosporidium than the Percoll-sucrose density gradient purification, which was the notation procedure of the Information Collection Requirements Rule (ICR) protozoan method. Recovery efficiencies of IMS were 78.6% (SD = 13.7%) and 69.3% (SD = 13.3%) for cysts and oocysts, respectively, in contrast to the 22.7% (SD = 14.5%) for cysts and 29.9% (SD = 20.3%) for oocysts by using Percoll-sucrose density gradient purification. In general, Giardia cysts attained a higher recovery efficiency. The recovery efficiencies of Method 1623, due to the use of Envirochek capsule filtration combined with the IMS, were 48.0% and 37.2% higher for Giardia and Cryptosporidium, respectively, than the ICR protozoan method for the three types of water.
Testing process capability based on C-pm in the presence of random measurement errors
(2005-12-01)
Pearn, WL
;
Shu, MH
;
Hsu, BM
;
工業工程與管理學系
;
Department of Industrial Engineering and Management
Process capability indices have been widely used in the manufacturing industry providing numerical measures on process performance. The index C-p provides measures on process precision (or product consistency). The index C-pm,C- sometimes called the Taguchi index, meditates on process centring ability and process loss. Most research work related to C-p and C-pm assumes no gauge measurement errors. This assumption insufficiently reflects real situations even with highly advanced measuring instruments. Conclusions drawn from process capability analysis are therefore unreliable and misleading. In this paper, we conduct sensitivity investigation on process capability C-p and C-pm in the presence of gauge measurement errors. Due to the randomness of variations in the data, we consider capability testing for C-p and C-pm to obtain lower confidence bounds and critical values for true process capability when gauge measurement errors are unavoidable. The results show that the estimator with sample data contaminated by the measurement errors severely underestimates the true capability, resulting in imperceptible smaller test power. To obtain the true process capability, adjusted confidence bounds and critical values are presented to practitioners for their factory applications.
The prevalence of Giardia and Cryptosporidium in Taiwan water supplies
(1999-06-11)
Hsu, BM
;
Huang, CP
;
Jiang, GY
;
Hsu, CLL
;
環境工程研究所
Giardia and Cryptosporidium have emerged as waterborne pathogens of concern. Thirty-one water samples were collected from nine potable water treatment plants in Taiwan and investigated for the presence of Giardia cysts and Cryptosporidium oocysts. The immunofluorescence assay was used for the simultaneous detection of cysts and oocysts. The frequency of occurrence of cysts was 77.8% for Giardia and 72.2% for Cryptosporidium in 18 raw water samples. Ten out of 13 samples collected from treated water samples showed the presence of cysts, while in 5 out of 13 treated water samples oocysts were detected. The risk assessment for adverse human effects arising from the presence of cysts and oocysts indicates the possibility of waterborne transmission of Giardia and Cryptosporidium infection in Taiwan if water is not adequately treated.