DESIGN AND IMPLEMENTATION OF STATE OBSERVERS IN REACTIVE DISTILLATION

This study demonstrates that state observers can be developed and applied to infer the composition profiles of reactive distillation columns from noise-contaminated temperature measurements. The design and implementation of a Kalman filter (KF) and a Luenberger observer (LO) are carried out, and their performances are quantitatively assessed. The reliability, accuracy, and robustness of the two designs method are examined and compared quantitatively. The design and implementation of a Luenberger observer are simpler and easier to carry out than those of a Kalman filter. On the other hand, a Kalman filter is found to be more robust to a noisy measurements, erroneous initial estimates, and model uncertainties. A Luenberger observer could be used for composition estimation of reactive distillation when an ideal model of the system can reasonably approximate the real system; otherwise, a Kalman filter is recommended to be applied in more practical situations.     

Ready steady push--a study of the role of arm posture in manual exertions

This study investigated arm posture and hand forces during bi-manual pushing. Nine male and eight female participants performed isometric exertions at two reach distances (0 and elbow-grip) and six different positions of the hand interface (handle), defined by the plane (longitudinal, lateral, horizontal) and orientation (0 degrees and 45 degrees). Electrogoniometer instruments were used to measure the displacements/postures of the wrist and elbow joints and the forearm, and force measuring strain gauges were used to measure the exerted hand forces (x-, y- and z-components). The results showed that ability to vary arm posture, particularly the forearm, is important during build up of force and that people tend to seek for a balance in the forces applied at the hands by exerting more in the vertical direction. Also, lateral plane handle positions permitted exertion of greater forces than longitudinal and horizontal plane positions.     

Post occupancy evaluation of green residential buildings,in the Greater Kuala Lumpur,Malaysia

Homebuyers are now demanding green buildings over conventional buildings due to better performance, higher operating savings, and the premium satisfaction that the green buildings offer. However, whilst the supply of green buildings is increasing, the satisfaction of the occupants requires evaluation. This research investigated the satisfaction of the occupants of certified residential green buildings in the Greater Kuala Lumpur. The research was based on a cross-sectional survey questionnaire comprising 15 performance factors and 118 green building occupants. The survey forms were administered through hand delivery. The satisfaction of the occupants with respect to the ability of the buildings to accommodate the elderly and the disabled was very high. The occupants were also satisfied with the acoustics, overall lighting, layout, and overall air quality of the buildings. The factor analysis structured the performance factors into four clusters, namely, lighting, indoor environmental quality, operating cost, and spatial. The findings will be useful for the design teams because developers and city planners and the green rating certifiers and facilitators make their decisions on the prioritisation of the performance criteria of the green buildings. Whilst the data were collected in Malaysia, the information is applicable to beyond Malaysia.

     

Online composition estimation and experiment validation of distillation processes with switching dynamics

This study explores both the theoretical and experimental investigations of applying a continuum and noncontinuum state estimator to composition estimation in a distillation process with switching dynamics. In a hybrid distillation modeling, the column compositions are considered as continuum states while the operating modes are modeled as noncontinuum states. A moving horizon estimator (MHE), which has the capability to handle process constraints is developed for composition estimation in a distillation process under known switching mode criteria using the available temperature measurements. The performance of a MHE is shown to be better than that of EKF in handling process and measurement noise under switching dynamics. For some situations where the system operating mode transition is unknown, a new approach to state estimation under unknown switching functions is investigated. The proposed method combines a MHE for composition estimation with a mode change detector to detect a change in the system operating mode and an operating mode estimator to identify the functioning mode. In the presence of both the measurement noise and plant-model mismatch, the developed estimator is shown to be effective in estimating both the column composition and the system operating mode accurately.     

Estimator-based control of reactive distillation system: Application of an extended Kalman filtering

This paper demonstrates that a state estimator can be successfully designed and implemented in a feedback control system of reactive distillation. The work of the state estimator is to provide the state compositions that are required to be used in the controller for necessary action. The control performance of a system that relies on the state estimator is examined and compared to a system that takes direct measurement from the process assuming the availability of a perfect online analyzer. It is found that the estimator-based system is robust against a moderate measurement errors and erroneous initial conditions. If the state estimator is designed from a highly erroneous process model, noisy measurements and approximate initial conditions, the use of estimator together with an online analyzer (for easily measured states) is recommended to achieve an effective control of a reactive distillation system.     

Rheological and physicochemical characterization of UAE crude oil

This study focuses on the rheological and physiochemical characterization of three samples of light crude oil and fuel oil from the United Arab Emirates. The dependence of density on temperature ranging from 20 to 200°C was determined. Also, the impact of temperature was investigated on viscosity, shear stress τ, shear rate, yield stress, and thixotropic behavior, and characterized by the Haake RheoStress. The exponential decrease of viscosity over temperature range was modeled using Arrhenius equation. The shear stress–viscosity data revealed that crude oil A solely exhibited Newtonian behavior while crude oils B and C and fuel oil followed the Herschel-Bulkley model.     

Development of a simultaneous continuum and noncontinuum state estimator with application on a distillation process

This study focuses on the development and application of a hybrid moving horizon estimator (HMHE) to achieve simultaneous estimation of both continuum and noncontinuum states in a constrained switching dynamic system. One of the major issues in a moving horizon estimation approach is the development of an arrival cost to summarize the effect of past and a prior information. In this work, we have developed a generalized arrival cost, which accounts for both continuum and noncontinuum states. A generalized hybrid state estimator, which can be used as a stand‐alone continuum state estimator, or as a simultaneous continuum and noncontinuum state estimator, is developed. The effects of constraints, process, and measurement noise levels, as well as a moving horizon length on the simultaneous estimation of both the continuum and noncontinuum states are analyzed. The effectiveness of the HMHE is demonstrated through simulation studies, while its practical reliability is tested by conducting experimental studies on a distillation column. © 2011 American Institute of Chemical Engineers AIChE J, 2012     

Failure Analysis in Graphite Epoxy Composite Laminates

The present analysis was performed to obtain bearing strength for pinned joints in uni-directional graphite epoxy composite laminates using characteristic curve model. The characteristic dimensions used to determine the characteristic curve were evaluated using a two-dimensional finite element model that was developed in ANSYS14.5 Software. Also, two-dimensional finite element stress analysis was developed to determine the stress distribution needed to evaluate the failure. Tsai-Wu failure criterion was used in the analysis with the characteristic curve to predict bearing strength. The results of the analysis showed good agreement with experimental data.