ROBUST CONTROLLER DESIGN FOR LOAD FREQUENCY CONTROL IN POWER SYSTEMS USING STATE-SPACE APPROACH

In this paper a robust governor has been designed using H∞ techniques to replace the conventional governor of the steam turbine of the power system to regulate the frequency of the power grid. The robust governor is synthesized using state-space approach with time variations, neglected dynamics, and constant main steam pressure are considered in the design process. The proposed approach ensures internal stability, satisfying both frequency and time domains requirements, and obtaining minimal performance H∞-norm of the closed-loop system in one burden. The simulations are carried out using MATLAB and the results show that the overall system output performance can be improved using the proposed H∞ robust governor

Diagnostic and Assessment Benefits and Barriers of BIM in Construction Project Management

This paper aims to diagnostic and assessment the benefits and barriers of Building Information Modelling in the construction project management. Both open and closed questionnaire was used to explore the views of a number of Iraqi engineers; in order to investigate the level of BIM implementation in Iraq construction sector. Questionnaire indicated an acceptable awareness of (BIM) in Iraq, especially among the young generation of engineers which indicates the arrival of the evolutionary stream of BIM in the next few years. Moreover, questionnaire showed that the most important advantage of implementing BIM in the Iraqi construction sector was the ability to generate accurate 2D plans at any stage, while the least important advantage was the ability to provide a careful planning of the site facilities, with a relative importance of (82 %) and (33 %) respectively. Furthermore, the most important barrier to its implementation was the unspecified responsibilities for data content, as presented by questionnaire, while the least important barrier was the lack of programs efficiency in data exchange and internal collaboration, with a relative importance of (81 %) and (34 %) respectively

Anti-Disturbance Compensation-Based Nonlinear Control for a Class of MIMO Uncertain Nonlinear Systems

Multi-Inputs-Multi-Outputs (MIMO) systems are recognized mainly in industrial applications with both input and state couplings, and uncertainties. The essential principle to deal with such difficulties is to eliminate the input couplings, then estimate the remaining issues in real-time, followed by an elimination process from the input channels. These difficulties are resolved in this research paper, where a decentralized control scheme is suggested using an Improved Active Disturbance Rejection Control (IADRC) configuration. A theoretical analysis using a state-space eigenvalue test followed by numerical simulations on a general uncertain nonlinear highly coupled MIMO system validated the effectiveness of the proposed control scheme in controlling such MIMO systems. Time-domain comparisons with the Conventional Active Disturbance Rejection Control (CADRC)-based decentralizing control scheme are also included

Reference values for the six-minute walk test in Nigerian adolescents aged 10 to 18 years

Objective: To determine baseline six-minute walk distance in Nigerian adolescents and establish its relationship with age, gender and anthropometric parameters.Methods: One hundred and eighty healthy adolescents (10 – 18 years) were recruited from three schools. Six-minute walk test was conducted as described by the American Thoracic Society. Demographic and anthropometric characteristics were related to achieve six-minute walk distance. A mathematical formula for predicting six-minute walk distance was generated.Results: The mean ± SD six-minute walk distance was 590.1 ± 72.02 m and was significantly longer in males (p= 0.001) among adolescents aged 10- 16 years. Age was the only characteristic significantly associated with six-minute walk distance following multiple linear regression analyses. The formulae, [six-minute walk distance = 317.3 + 21.5 x age (years) in males and 117 + 33.0 x age (years) in females] closely approximated to measured six-minute walk distance.Conclusion: This study has derived reference values for 6-minute walk test in adolescents; the use of these reference values should consider age and gender variations.Keywords: Exercise test; Six-minute-walk; Adolescents; Nigeri

Synthesis of Calcium-Zincon Complex and Exploitation it in the Assembly of Calcium Ion-Selective Electrode.

A new calcium ion-selective electrode was assembled from complex synthesized by calcium ion and zincon which doped in pvc with suitable mediator and solvent . The prepared complex was identified by UV- Visible and IR spectrophotometry. The new electrode was characterized by its high slope (29.55 ±0.02 mV/decade) compared with calcium phosphate electrode (26.67±0.022 mV/decade) and long lifetime (10 months) . The linear range of the electrode was 10-5-10-1M and the detaction limit was 10-5M . Response time was in the range of 20-60 seconds depending on the concentration of the solution and the lifetime of the electrode. The electrode was linearly working at a pH of (5-10). Most of anions were severely interfered and these were exploited to determine calcium and the anions in precipitation titrations . Cations were slightly interfered especially at high interferent concentrations . The new electrode was applied for the determination of calcium in tap water which offered excellent results compared with flame emission photometric method

The impact of electronic versus paper-based data capture on data collection logistics and on missing scores in thyroid cancer patients.

The purpose of this study was to investigate the impact of the type of data capture on the time and help needed for collecting patient-reported outcomes as well as on the proportion of missing scores. In a multinational prospective study, thyroid cancer patients from 17 countries completed a validated questionnaire measuring quality of life. Electronic data capture was compared to the paper-based approach using multivariate logistic regression. A total of 437 patients were included, of whom 13% used electronic data capture. The relation between data capture and time needed was modified by the emotional functioning of the patients. Those with clinical impairments in that respect needed more time to complete the questionnaire when they used electronic data capture compared to paper and pencil (OR <sub>adj</sub> 24.0; p = 0.006). This was not the case when patients had sub-threshold emotional problems (OR <sub>adj</sub> 1.9; p = 0.48). The odds of having the researcher reading the questions out (instead of the patient doing this themselves) (OR <sub>adj</sub> 0.1; p = 0.01) and of needing any help (OR <sub>adj</sub> 0.1; p = 0.01) were lower when electronic data capture was used. The proportion of missing scores was equivalent in both groups (OR <sub>adj</sub> 0.4, p = 0.42). The advantages of electronic data capture, such as real-time assessment and fewer data entry errors, may come at the price of more time required for data collection when the patients have mental health problems. As this is not uncommon in thyroid cancer, researchers need to choose the type of data capture wisely for their particular research question

Molecular imaging in oncology: the acceptance of PET/CT and the emergence of MR/PET imaging

In the last decade, PET-only systems have been phased out and replaced with PET-CT systems. This merger of a functional and anatomical imaging modality turned out to be extremely useful in clinical practice. Currently, PET-CT is a major diagnostic tool in oncology. At the dawn of the merger of MRI and PET, another breakthrough in clinical imaging is expected. The combination of these imaging modalities is challenging, but has particular features such as imaging biological processes at the same time in specific body locations

Global economic burden of unmet surgical need for appendicitis

Background: There is a substantial gap in provision of adequate surgical care in many low-and middle-income countries. This study aimed to identify the economic burden of unmet surgical need for the common condition of appendicitis. Methods: Data on the incidence of appendicitis from 170 countries and two different approaches were used to estimate numbers of patients who do not receive surgery: as a fixed proportion of the total unmet surgical need per country (approach 1); and based on country income status (approach 2). Indirect costs with current levels of access and local quality, and those if quality were at the standards of high-income countries, were estimated. A human capital approach was applied, focusing on the economic burden resulting from premature death and absenteeism. Results: Excess mortality was 4185 per 100 000 cases of appendicitis using approach 1 and 3448 per 100 000 using approach 2. The economic burden of continuing current levels of access and local quality was US $92 492 million using approach 1 and$73 141 million using approach 2. The economic burden of not providing surgical care to the standards of high-income countries was $95 004 million using approach 1 and$75 666 million using approach 2. The largest share of these costs resulted from premature death (97.7 per cent) and lack of access (97.0 per cent) in contrast to lack of quality. Conclusion: For a comparatively non-complex emergency condition such as appendicitis, increasing access to care should be prioritized. Although improving quality of care should not be neglected, increasing provision of care at current standards could reduce societal costs substantially