Wen-Pei Sung

Application of Nanoscale Silver-Doped Titanium Dioxide as Photocatalyst for Indoor Airborne Bacteria Control: A Feasibility Study in Medical Nursing Institutions

Abstract The deterioration of indoor air quality because of airborne bacterial consortia is a widespread environmental problem. The main objective of this study is to evaluate the feasibility of applying nanoscale silver-doped titanium dioxide (TiO2) photocatalysis (nano-Ag/TiO2) particles as a photocatalyst to enhance the disinfecting capability of bacterial restraining equipment in a medical nursing institution. A full-scale, on-site study was initiated to test the effectiveness of adding the photocatalyst to various air quality control equipments; that is, fixed full-covering type (FF type), underneath swinging type (US type), and lateral swinging type (LS type). Results from this study indicate that the FF type has the best bacterial restraining rate (81%) as compared with the LS type (66%) and the US type (61%). Similar results are obtained at different heights (90 and 180 cm) of the nursing institutions, revealing that freshly disinfected air is provided regardless of location as long as the air quality control equipment is in operation. The proposed equipment can disinfect air to effectively restrain bacteria as demonstrated on-site in medical nursing institutions; the results will also be for designing integrated, commercialized, large-scale applications in the future.

A Linearization Model for the Displacement Dependent Semi-active Hydraulic Damper

In earthquake engineering, a hydraulic damper is a kind of energy-dissipating device to reduce the structural response. Newly developed Displacement Dependent Semi-Active Hydraulic Damper (DSHD) is one of the hydraulic dampers. For this damper, the hydraulic cylinder is acting as a damper connector. This damper connector is like a flexible switch with tight-loose and close-open functions and is used to connect a structure and a resistance component. For a DSHD-added structure, to linearize the nonlinear behavior of DSHD is required for preliminary design. Using the damping ratio as a parameter, the DSHD is modeled as a fixture of a linear spring and linear viscous damper. This approach is valid for application in the engineering practice.

Testing and modeling for energy dissipation behavior of velocity and displacement dependent hydraulic damper

A passive energy-dissipating device, velocity, and displacement dependent hydraulic damper (VDHD), is developed to reduce the seismic response of structure. This device is comprised of a hydraulic jack, check valve, relief valve, and throttle valve. The numerical analysis model for SAP2000 nonlinear analysis program is proposed to simulate the energy-dissipating characteristics of VDHD. The analysis results of this model compared with the seismic resistant tests reveal that this proposed model can accurately describe the actual energy-dissipating behavior of VDHD. The efficiency of VDHD is confirmed using this proposed model for carrying out numerical analyses of bare building, building added with bulking resistant bracing (BBR), and VDHD. The energy-dissipating capabilities of VDHD are performing excellent displacement and acceleration control with various ground magnitudes; being an energy absorber to absorb mechanical energy in the structure and resist structural movement; and gathering the advantage of BRB.

Quantification and Analysis of Airborne Bacterial Characteristics in a Nursing Care Institution

ABSTRACT Indoor air quality has become a critical issue because people spend most of their time in the indoor environment. The factors that influence indoor air quality are very important to environmental sanitation and air quality improvement. This study focuses on monitoring air quality, colony counts, and bacteria species of the indoor air of a nursing care institution. The regular colony counts in two different wards range from 55 to 600 cfu m−3. Regression analysis results indicate that the bacterial colony counts have close correlation with relative humidity or carbon dioxide (CO2) but not with carbon monoxide (CO) or ozone (O3). Real-time PCR was used to quantify the bacterial pathogens of nosocomial infection, including Acinetobacter baumannii, Citrobacter freundii, Escherichia coli, Klebsiella pneumoniae, and methicillin-sensitive Staphylococcus aureus. The most abundant bacteria species in the air of the nursing care institution is E. coli. IMPLICATIONS Indoor temperature, humidity, ventilation, accumulation of biological pollutants, and potential infection problems will seriously affect the indoor environments. Studying these factors is important to indoor environmental sanitation and air quality improvements. Results of using real-time PCR to evaluate the bacterial pathogens of nosocomial infection for a nursing care institution in Taiwan reveal that the main bacteria species existing in the indoor air is E. coli.

PREDICTIVE CONTROL AND SIGNAL ON NOISE REDUCTION FOR SEMI-ACTIVE HYDRAULIC DAMPER

In the implementation of active or semi-active control systems, it is necessary to process the measured signals because they are not perfect in reality. At present, the current energy-dissipating method for controlling semi-active dampers is flawed because of some restrictions on processing and measuring the signals. Thus, a detection methodology of signal control is proposed in this research based on the direction of structural motion; a velocity estimating calculator is developed by using the least-square polynomial regression. Comparison of the analytical results and experimental data confirms that the proposed calculator is effective in predicting when to switch the moving direction of a semi-active damper. It can detect when the direction of the structure motion reverses as well as when to compensate the poor influence on the performance of a semi-active damper caused by the delayed response. Additionally, the noise of displacement signal will not affect the phase difference of predictive signals.

Developing Dynamic Digital Image Techniques with Continuous Parameters to Detect Structural Damage

Several earthquakes with strong magnitude occurred globally at various locations, especially the unforgettable tsunami disaster caused by the earthquake in Indonesia and Japan. If the characteristics of structures can be well understood to implement new technology, the damages caused by most natural disasters can be significantly alleviated. In this research, dynamic digital image correlation method for using continuous parameter is applied for developing a low-cost digital image correlation coefficient method with advanced digital cameras and high-speed computers. The experimental study using cantilever test object with defect control confirms that the vibration mode calculated using this proposed method can highly express the defect locations. This proposed method combined with the sensitivity of Inter-Story Drift Mode Shape, IDMS, can also reveal the damage degree of damage structure. These test and analysis results indicate that this proposed method is high enough for applying to achieve the object of real-time online monitoring of structure.

Using Enhanced Landfarming System to Remediate Diesel Oil-Contaminated Soils

The objective of this study was to assess the potential of applying enhanced landfarming system on the treatment of diesel-oil contaminated soils. Laboratory reactors were conducted to determine the optimal operational conditions of the modified landfarming. Except of frequent soil tilling for air replacement, different additive was added in each reactor enhance the removal efficiency of total petroleum hydrocarbon (TPH). The additives used in this study included kitchen waste compost, petroleum-hydrocarbon (PH) degrading bacteria, rice husks, and activated sludge. PH-degrading bacteria were isolated from PH contaminated soils and activated sludge was collected from a wastewater treatment plant containing PH in the influent. PH-degrading bacteria and sludge were added to increase the microbial population and diversity. Rice husk was used as the bulking agent (soil to bulking agent volume ratio = 3:1) to increase the soil permeability. The compost (soil to compost volume ratio = 3:1) was used as organic amendment to increase both the microbial population and soil permeability. Results indicate that the highest first-order TPH decay rate and removal ratio were approximately 0.1 day-1 and 92.4%, respectively, observed in reactor containing compost. In the compost reactor, TPH dropped from 5,900 to 450 mg/kg and total viable bacterial counts increased from 9.4×105 to 7.2×108 cfu/g of soil within 25 days of incubation. This indicates that the kitchen waste compost contained high microbial population and organic content, which could cause the rapid bacterial growth and enhance the TPH degradation. The TPH removal ratios for sludge, PH-degrading bacteria, rice husks, and control reactors were 86.9, 83.1, 79.7, and 54%, respectively. This indicates that the soil tilling played an important role in the landfarming system, and significant amount of TPH removal was due to the volatilization mechanism. Adding sludge or PH-degrading bacteria could cause the increase in both the total microbial population and specific PH-degrading microbial consortia, which caused the increased TPH removal efficiency.

Validity of the displacement dependent semi-active hydraulic damper used in a structure

In structural engineering, the damping device is the best way to equip the structure for resisting earthquakes. The newly developed displacement dependent semi-active hydraulic damper (DSHD) is a kind of hydraulic damper to reduce the structural response. The DSHD is a fixture connecting the brace and the structure. At a seismic loading, the DSHD is functioned to dissipate the energy at the transition of bracing from the tensile constraint to the compressive constraint or in reverse. When a structure suffers a large seismic excitation, the overflow function is triggered to prevent the failure of a bracing member. That is, at the stress in the linked brace reaching a certain value, it will start the opening of the overflow valve maintaining an aptotic pressure for confining the bracing deformation within the design value. This DSHD provides availability for resisting excessive vibration in the structural design. In this paper, the analysis modeling is set up for simulating the nonlinear behavior of DSHD. The performance of DSHD is investigated in the nonlinear analysis for seismic evaluation.

Applying Outdoor Environment to Develop Health, Comfort, and Energy Saving in the Office in Hot-Humid Climate

A human life demand set to emerge in the future is the achievement of sustainability by maintaining a comfortable indoor environment without excessive reliance on energy-consuming air conditioners. The major research processes in this study are: (1) measuring indoor air quality and thermal comfort to evaluate the comfort of an indoor environment; (2) implementing questionnaire survey analysis to explore peoples environmental self-perceptions and conducting a meta-analysis of the measurement results for air quality and physical aspects; and (3) constructing an indoor monitoring and management system. The experimental and analysis results of this research reveal that most of the office occupants preferred a cooler environment with a lower temperature. Additionally, because the summers in Taiwan are humid and hot, the occupants of an indoor space tend to feel uncomfortable because of the high humidity and poor indoor air quality. Therefore, Variable Air Volume (VAV), two air intakes, and exhaust plant are installed to improve indoor environment. After improvement, a lower temperature (approximately 21.2–23.9°C) indirectly reduces humidity, thereby making the occupants comfortable. Increasing air velocity to 0.1 ~ 0.15 m/s, the carbon dioxide concentrations decrease below the requirement of the WHO. Ninety-five percent of the workers corresponded to the standard comfort zone after this improvement.

Developing three-dimensional digital image correlation techniques to detect the surface smoothness of construction materials

A low-cost three-dimensional digital image correlation coefficient method, 3-D DIC equipped with one advanced digital camera and high-speed computer to detect the flatness of plaster of Paris casts is proposed in this research. The test and analysis results show that this proposed method can easily reveal the rugged surface of plaster cast. No matter what the absolute displacement, rotate on z-axis, strain on z-axis and von Mises strain of analysis results are extremely close to the real situation of this test sample. Then, the joint roughness coefficient (JRC) is used to compare the test results of 3-D DIC with the test results of laser scanner. These results indicate that the JRC values measured by laser scanner are very similar to that measured by 3-D DIC. Therefore, the accuracy degree of this 3-D DIC method is high enough for applying it to achieve the three-dimensional surface smoothness of construction material.