CD Moisture Profile Disturbances in Tissue Production - Their Origins and possible Control

The origins of poor CD (cross machine) moisture profiles In tissue production are discussed generally. CD line force distribution at the first and second presser roll has a significant influence on the CD moisture profile. The crowning of cylinder and presser rolls compensates for the deformation of the Yankee cylinder shell (due to nip load, internal steam pressure and hood operating conditions) and of the presser rolls but only for any one given operating condition. However, during operation the parameters often have to be varied. in a sensitivity analysis the resulting CD line force deviations were calculated and typical figures are given here to demonstrate the relative effect. The shape of the resulting line load curves are drawn and from these the typical shape of the resulting CD moisture- profile can be derived. Means for possible control such as controllable presser rolls, sectionally adjustable hoods and steam boxes as well as eddy current and infra-red -heating are discussed and evaluated.     

Flood Avoidance Mechanisms for Bridged Resilient Packet Rings

Resilient Packet Ring (RPR), or the Standard IEEE 802.17, is a new IP-based network technology proposed to replace SONET/SDH in metropolitan area networks. RPR is well-adapted to handle multimedia traffc and is effcient. However, when RPR networks are bridged, inter-ring packets, or packets with the destination on a remote RPR network other than on the source network, are flooded on the source and the destination networks, and also on the path of the intermediate networks between the source and the destination networks. This decreases the available bandwidth for other traffc in those networks and is ineffcient. As a result, we propose two solutions based on topology discovery, global topology discovery (GTD) and enhanced topology discovery (ETD), that prevent the flooding of inter-ring packets. GTD enables the bridges to determine the next-hop bridge for each destination. ETD enables the source node to determine a default ringlet, so that packets reach the next-hop bridge without flooding the source network. The proposed solutions were analyzed and the overhead bandwidth and stabilization time were shown to be bounded. Simulations performed showed that the proposed solutions successfully avoid flooding and achieve optimal effciency in the intermediate and destination networks, and in the source networks with one bridge.     

Evaluation of the Thermal Comfort of a Thermoelectric Ceiling Cooling Panel (TE-CCP) System

This present work evaluates the cooling performance and thermal comfort of a thermoelectric ceiling cooling panel (TE-CCP) system composed of 36 TE modules. The cold side of the TE modules was fixed to an aluminum ceiling panel to cool a test chamber of 4.5 m³ volume, while a copper heat exchanger with circulating cooling water at the hot side of the TE modules was used for heat release. Thermal acceptability assessment was performed to find out whether the indoor environment met the ASHRAE Standard-55's 80% acceptability criteria. The standard was met with the TE-CCP system operating at 1 A of current flow with a corresponding cooling capacity of 201.6 W, which gives the COP of 0.82 with an average indoor temperature of 27°C and 0.8 m/s indoor air velocity.     

Measurement and prediction of diffusion coefficients of supercritical CO2 in molten polymers

The solubility and diffusivity of supercritical carbon dioxide (sc‐CO₂) in low‐density polyethylene (LDPE), high‐density polyethylene (HDPE), polypropylene (PP), ethylene‐ethylacrylate copolymer (EEA) and polystyrene (PS) were measured at temperatures from 150°C to 200°C and pressures up to 12 MPa by using the Magnetic Suspension Balance (MSB), a gravimetric technique for gas sorption measurements. The solubility of CO₂ in each polymer was expressed by Henry's constant. The interaction parameter between CO₂ and polymer could be obtained from the solubility data, and it was used to estimate the Pressure‐Volume‐Temperature relationship and the specific free volume of polymer/CO₂ mixtures. The diffusion coefficients were also measured by the MSB for each polymer. The resulting diffusion coefficients were correlated with the estimated free volume of polymer/CO₂ mixture. Combining Fujita's and Maeda and Paul's diffusion models, a model was newly developed in order to predict diffusion coefficients for the polymers studied. Polym. Eng. Sci. 44:1915–1924, 2004. © 2004 Society of Plastics Engineers.     

Thermal stability and cathodoluminescence of potassium strontium vanadates

We have studied the thermal stability of five potassium strontium vanadates: KSr(VO₃)₃, K₂Sr(VO₃)₄, K₄Sr(VO₃)₆, K₆Sr(VO₃)₈, and KSrVO₄. The double orthovanadate undergoes a reversible polymorphic transformation at 1117°C and is stable up to 1500°C. The double metavanadates melt peritectically in the range 490–517°C to give Sr₂V₂O₇ crystals and peritectic melt. Pulsed cathodoluminescence studies have shown that the potassium: strontium ratio in the vanadates and their crystal structure have little effect on their optical emission properties. The performance parameters of new vanadate-based phosphors have been determined.     

Sound Pressure Level in an Infant Incubator

Currently, there are a lot of infant incubators being used in hospitals in Thailand. That situation brings about the question on whether the values of physical quantities such as sound pressure or temperature inside the incubator still conform to the requirements of the international standards. The main objective of this research was to study the sound pressure level (SPL) generated within the incubator. The measurement method was based on IEC 60601-2-19:2009. There were two measurement conditions of the SPL in the infant incubator; the measurement during power-off condition and the measurement during the operation of incubator at a controlled temperature of 36 °C with a maximum humidity setting. Both measurement conditions were carried out in an empty incubator. The average values from the three measurement results of each operating incubator subtracted by the value of background noise were reported as the result of SPL generated in the incubator. The SPL results from this study were lower than 60 dBA, which are within the tolerance limit specified in IEC 60601-2-19. The estimated measurement uncertainty was lower than 1.8 dBA. This research will benefit to an investigation of hearing loss in infants possibly caused by the operation of the infant incubators in Neonatal Intensive Care Unit (NICU). Ultimately, this research will be a great evidence to show the NICU staffs in the hospitals in Thailand and also raise their awareness that it is important to sustain the proper maintenance and calibration of the infant incubators.     

Fracture of the ossified Achilles tendon

OBJECTIVE: To analyse the relation between induced abortion and risk of subsequent miscarriage. DESIGN: Case-control study conducted between February 1990 and May 1995. PARTICIPANTS: Case group included 782 women (median age 32 years, range 14-46) admitted for spontaneous abortion (within the 12th week of gestation) to a network of obstetric departments in the greater Milan area. The control group was recruited among women who gave birth at term (> 37 weeks of gestation) to healthy infants on randomly selected days at the hospitals where cases had been identified. A total of 1543 controls (median age 30 years, range 14-45) were interviewed. RESULTS: A total of 102 cases (13%) and 181 controls (12%) reported one or more induced abortions. No clear relation emerged between miscarriage and induced abortions. In comparison with women reporting no induced abortion the odds ratio (OR) for miscarriage were 1.1 (95% CI 0.8-1.4) in women reporting one induced abortion and 0.9 (95% CI 0.4-1.8) in women reporting two or more. Likewise, there was no association between time since last and age at first induced abortion and risk of miscarriage. CONCLUSIONS: This study did not find any strong association between induced and spontaneous abortion.     

Prediction of low bone mineral density in postmenopausal women by artificial neural network model compared to logistic regression model

Measuring bone mineral density (BMD) is currently the best modality to diagnose osteoporosis and predict future fractures. The use of risk factors to predict BMD and fracture risk has been considered to be inadequate for precise diagnostic purpose, but it may be helpful as a screening tool to determine who actually needs BMD assessment. Recently, artificial neural network (ANN), a nonlinear computational model, has been used in clinical diagnosis and classification. In the present study, we evaluated the risk factors associated with low BMD in Thai postmenopausal women and assessed the prediction of low BMD using an ANN model compared to a logistic regression model. The subjects consisted of 129 Thai postmenopausal women divided into 2 groups, 100 subjects in the training set and the remaining 29 subjects in the validation set. The subjects were classified as having either low BMD or normal BMD by using BMD value 1 SD lower than the mean value of young adults as the cutoff point. Decreased body weight, decreased hip circumference and increased years since menopause were found to be associated with low BMD at the lumbar spine by logistic regression. For the femoral neck, increased age and decreased urinary calcium were associated with low BMD. The models had a sensitivity of 85.0 per cent, a specificity of 11.1 per cent and an accuracy of 62.0 per cent for the diagnosis of low BMD at the lumbar spine when tested in the validation group. For the femoral neck, the sensitivity, specificity and accuracy were 90.5 per cent, 12.5 per cent, and 69.0 per cent, respectively. Models based on ANN correctly classified 65.5 per cent of the subjects in the validation group according to BMD at the lumbar spine with a sensitivity of 80.0 per cent and a specificity of 33.3 per cent while it correctly classified 58.6 per cent of the subjects at the femoral neck with a sensitivity of 76.2 per cent and a specificity of 12.5 per cent. There was no significant difference in terms of accuracy, sensitivity and specificity in the prediction of low BMD at the lumbar spine or the femoral neck between ANN model and logistic regression model. We concluded that ANN does not perform better than convention statistical methods in the prediction of low BMD. The less than perfect performance of the prediction rules used in the prediction of low BMD may be due to the lack of adequate association between the commonly used risk factors and BMD rather than the nature of the computational models.     

Preparation of carbon aerogel microspheres by a simple-injection emulsification method

Carbon aerogel microspheres were successfully prepared using a simple-injection emulsification method, employing sol–gel polycondensation of a resorcinol–formaldehyde solution containing sodium carbonate as a catalyst. This process was followed by solvent exchange using acetone, supercritical drying with carbon dioxide and carbonization in a nitrogen atmosphere. The effect of curing time before starting injection, injection rate and agitation rate of continuous phase on the particle size and the porous properties of the carbon aerogel microspheres was investigated. Adsorption of phenol by using the prepared carbon aerogel microspheres was also examined. The diameter of carbon aerogel microspheres was controlled in the range of 20–55 μm by varying injection rate and agitation rate. The mean diameter of carbon aerogel microspheres decreased with increasing the injection rate and the agitation rate, whereas their mean diameter was independent of the curing time. The BET surface area and total pore volume of carbon aerogel microspheres increased with increasing the curing time. In contrast, their BET surface area and total pore volume decreased with increasing the injection rate and the agitation rate. The BET surface area, total pore volume, mesopore volume and micropore volume of the carbon aerogel microspheres with a mean diameter of 45 μm were 903 m²/g, 0.60 cm³/g, 0.31 cm³/g and 0.27 cm³/g, respectively. The phenol-adsorption capacity of these carbon aerogel microspheres was 29.3 mg phenol/g adsorbent.     

Capacitance measurements of photovoltaic cells based on mixed monolayers of chlorophyll a and sulfoquinovosyldiacylglycerol

The capacitance measurements of Al/Chlorophyll a/Ag and Al/Chlorophyll a-Sulfoquinovosyldiacylglycerol/Ag sandwich cells have been carried out at different frequencies in dark and under illumination. The results show that while a voltage-dependent capacitance and a linear 1/C² versus V_a plot is obtained for chlorophyll a (Chl a) at low frequencies, the addition of sulfoquinovosyldiacylglycerol (SQDG) in proportions 0.25 results in totally voltage-invariant capacitance. The capacitance characteristic of Chi a-SQDG (0.25) cells resemble more those for an insulator than those for a Schottky barrier. These results are explained in terms of negatively charged SQDG playing a role of traps which immobilize the holes. Alternatively, the interaction of negative polar head group of SQDG with Mg²⁺ of Chl a can also be invoked as a possible reason for the observed results. The bound Chl a- SQDG species possibly does not form a Schottky barrier or forms a weak barrier with either Al or Ag electrodes, resulting in insulator-like capacitance characteristics of Al/Chl a-SQDG(0.25)/Ag cells.