Nonlinear System Identification Using Recurrent Networks

This paper presents empirical results on the application of neural networks to system identification and inverse system identification. Recurrent and Feedforward network models are used to build an emulator of a simple nonlinear gantry crane system, and for the inverse dynamics of the system. Recurrent networks were observed to perform slightly better than feedforward networks for these problems

Prediction Criteria for Successful Weaning from Respiratory Support: Statistical and Connectionist Analyses

Objective: To develop predictive criteria for successful weaning from mechanical assistance to ventilation based upon simple clinical tests using discriminant analyses and neural network systems. Design: Retrospective development of predictive criteria and subsequent prospective testing of the same. Setting: Medical intensive care unit of a 300-bed teaching veterans administration hospital. Patients: Twenty-five ventilator-dependent elderly patients with acute respiratory failure. Interventions: Routine measurements of negative inspiratory force (NIF), tidal values (VT), minute ventilation (VE), respiratory rate (RR), vital capacity (FVC), and maximum voluntary ventilation (MVV), followed by weaning trial. Success or failure in 21 efforts analyzed by linear and quadratic discriminant model and neural network formulas to develop prediction criteria. The criteria so developed were tested for predictive power prospectively in nine trials in six patients. The analyses thus obtained predicted the success or failure of weaning within 9O-lOO% accuracy. Conclusion: Use of quadratic discriminant and neural network analyses could be useful in developing accurate predictive criteria for successful weaning based upon simple bedside measurements

DUKKU AND BAEKAM SPRINGWATER INHIBIT THE UREASE ACTIVITY OF HELICOBACTER PYLORI

Background: Springwater (SW) contains many kinds of minerals such as sodium, potassium and copper. These metallic ions may influence the activity of metallo-enzymes such as urease via competitive inhibition. In this study, we investigated the effect of SW on the inhibition of Ni-containing urease activity, which is essential for the colonization of Helicobacter pylori (H. pylori) in the human stomach.Materials and Methods: We studied the growth inhibition of H. pylori by SW. We evaluated ammonia production to detect urease activity and performed western blot analysis of UreA and UreB for enzyme production.Results: SW had no significant effect on bacterial growth. Western blot analysis also showed that SW did not affect the translation of UreA and UreB, but it significantly reduced the urease activities of the Jack bean as well as that of H.pylori from 50 to 75%.Conclusion: These results might indicate that the consumption of SW may prevent the colonization of H. pylori andameliorate the toxic effect on gastric mucosa via the inhibition of urease activity

Type I Saikosaponins A and D Inhibit Osteoclastogenesis in Bone Marrow-Derived Macrophages and Osteolytic Activity of Metastatic Breast Cancer Cells

Many osteopenic disorders, including a postmenopausal osteoporosis and lytic bone metastasis in breast and prostate cancers, are linked with a hyperosteoclast activity due to increased receptor activator of nuclear factor kappa-B ligand (RANKL) expression in osteoblastic/stromal cells. Therefore, inhibition of RANKL-induced osteoclastogenesis and osteoclast-induced bone resorption is an important approach in controlling pathophysiology of these skeletal diseases. We found that, of seven type I, II, and III saikosaponins isolated from Bupleurum falcatum, saikosaponins A and D, type I saikosaponins with an allyl oxide linkage between position 13 and 28 and two carbohydrate chains that are directly attached to the hydroxyl groups in position 3, exhibited the most potent inhibition on RANKL-induced osteoclast formation at noncytotoxic concentrations. The stereochemistry of the hydroxyl group at C16 did not affect their activity. Saikosaponins A and D inhibited the formation of resorptive pits by reducing the secreted levels of matrix metalloproteinase- (MMP-) 2, MMP-9, and cathepsin K in RANKL-induced osteoclasts. Additionally, saikosaponins A and D inhibited mRNA expression of parathyroid hormone-related protein as well as cell viability and invasion in metastatic human breast cancer cells. Thus, saikosaponins A and D can serve as a beneficial agent for the prevention and treatment of osteoporosis and cancer-induced bone loss

Efficient techniques for multimedia transmission over packet-switched cellular networks

In packet-switched cellular networks, base stations corresponding to different cells are connected by wired transmission links to cover the wide area, while communication in a cell takes place over wireless channels. All streams of messages are divided into packets. We consider two types of channel/link impairments in packet-switched cellular networks, bit errors and packet losses. In wireless channels, bit errors occur due to channel impairments such as fading, interference and noise. In addition, congestion at the intermediate nodes and at shared resources in wired links causes packet losses. Bit errors and packet losses are dominant impairments in packet-switching cellular networks and limit system performance. Multimedia information such as imagery and video is becoming an important part of traffic over such networks. These impairments such as bit errors and packet losses significantly impact the quality of service (QoS) of applications and degrade their performance. In this dissertation, a number of techniques for efficient transmission of multimedia information over packet-switched cellular networks are presented. For the uplink channel in DS-CDMA systems, multiuser detection and channel decoding can be performed jointly to improve the performance of systems. We propose a new joint detection-decoding (JDD) receiver with significantly less complexity and slight reduction in performance. This joint detection-decoding receiver can be employed in multimedia applications such as image transmission for more efficient operation. The other impairments, packet losses, need to be corrected at the receiver for reliable communication. Packet-level forward error correction (FEC) schemes can be improved when they adapt to network conditions. These adaptive FEC schemes outperform the static FEC scheme in terms of the packet loss rate. Utilizing the concept of gaps that is motivated by the Markov gap model for packet losses over the Internet, adaptive FEC schemes can be further improved. We study the packet loss process and investigate its modeling using the Markov gap model. Furthermore, a gap-based adaptive FEC scheme for packet-loss recovery is proposed. We employ these new transmission approaches for image/video transmission over packet-switched cellular networks and demonstrate superior performance

A Receiver-Initiated MAC Protocol for Wireless Sensor Networks Based on Tree Topology

This paper proposes receiver-initiated X-MAC with tree topology (TRIX-MAC), an improved energy-efficient MAC protocol based on an asynchronous duty cycling for wireless sensor networks with tree topology. TRIX-MAC improves energy efficiency through utilizing short preambles and adopting the receiver-initiated approach that minimizes sender nodes' energy consumption by enabling transmitters to predict receiver nodes' wake-up times and reduces receiver nodes' energy consumption by decreasing the number of control frames. In many sensor network applications, the data flow from source nodes to a sink forms a unidirectional tree. A property of tree topology, the parent-child relation, is also exploited to reduce the likelihood of collisions between frames sent by children nodes. We use the network simulator, ns-2, to evaluate TRIX-MAC's performance. Compared to the prior asynchronous duty cycling approaches of X-MAC, RIX-MAC, and PW-MAC, the proposed protocol shows better performance in terms of throughput, energy efficiency, and end-to-end delay

Investigation of Pedestrian Comfort with Wind Chill during Winter

Two types of methods are used to evaluate pedestrian comfort: pedestrian wind comfort and outdoor thermal comfort. To accurately ascertain the outdoor wind environment, wind speed is the only parameter considered. However, pedestrians may still feel discomfort when the perceived temperature is low, even though the wind comfort criterion has been satisfactorily fulfilled. The purpose of this study is, therefore, to investigate pedestrian comfort when the perceived temperature is low, especially in winter conditions. To achieve this, a pedestrian survey was conducted, and 588 respondents completed a questionnaire. The results show that pedestrians feel discomfort when the WCET (Wind Chill Equivalent Temperature) is low, with almost 40 percent of respondents answering that they feel discomfort in these conditions. In conclusion, the threshold wind speed of the winter season could be determined to be lower than that of the existing comfort criteria by applying the WCET

CFD simulation analysis on integrated operation of range-hood and make-up air supply for cooking-generated particulate matter

One of the most important problems of cooking-generated particulate matter (PM) is that it rapidly disperses when the range hood is in operation during cooking. To improve the performance of the range hood and prevent the dispersion of PM, a supply of make-up air equivalent to the airflow rate of the range hood should be provided. In this regard, we place an auxiliary supply system as a make-up supply to solve such problems. The objective of this study is to evaluate the performance of the make-up air supply system and the range hood. To evaluate this system, several case studies were performed involving CFD simulations. The auxiliary supply system is optimized through three types of variables (size of diffuser, distance from the source, and flow angle). An increase in the length of the diffuser causes PM dispersion to decrease. The installation of the diffuser at a certain distance from the emission source is effective in preventing dispersion of cooking-generated PM. In the building analyzed in this study, supplying the make-up air at an angle of 10° was observed to be most effective

Assessment of a Real-Time Prediction Method for High Clothing Thermal Insulation Using a Thermoregulation Model and an Infrared Camera

For evaluating the thermal comfort of occupants, human factors such as clothing thermal insulation (clo level) and metabolic rate (Met) are one of the important parameters as well as environmental factors such as air temperature (Ta) and humidity. In general, a fixed clo level is commonly used for controlling heating, ventilation, and air conditioning using the thermal comfort index. However, a fixed clo level can lead to errors for estimating the thermal comfort of occupants, because clo levels of occupants can vary with time and by season. The present study assesses a method for predicting the clo level of occupants using a thermoregulation model and an infrared (IR) camera. The Tanabe model and the Fanger model were used as the thermoregulation models, and the predicted performance for high clo level (winter clothing) was compared. The skin and clothing temperatures of eight subjects using a non-contact IR camera were measured in a climate chamber. In addition, the measured values were used for the thermoregulation models to predict the clo levels. As a result, the Tanabe model showed a better performance than the Fanger model for predicting clo levels. In addition, all models tended to predict a clo level higher than the traditional method