Nonlinear control for Two-Link flexible manipulator

Recently the use of robot manipulators has been increasing in many applications such as medical applications, automobile, construction, manufacturing, military, space, etc. However, current rigid manipulators have high inertia and use actuators with large energy consumption. Moreover, rigid manipulators are slow and have low payload-to arm-mass ratios because link deformation is not allowed. The main advantages of flexible manipulators over rigid manipulators are light in weight, higher speed of operation, larger workspace, smaller actuator, lower energy consumption and lower cost. However, there is no adequate closed-form solutions exist for flexible manipulators. This is mainly because flexible dynamics are modeled with partial differential equations, which give rise to infinite dimensional dynamical systems that are, in general, not possible to represent exactly or efficiently on a computer which makes modeling a challenging task. In addition, if flexibility nature wasn\u27t considered, there will be calculation errors in the calculated torque requirement for the motors and in the calculated position of the end-effecter. As for the control task, it is considered as a complex task since flexible manipulators are non-minimum phase system, under-actuated system and Multi-Input/Multi-Output (MIMO) nonlinear system. This thesis focuses on the development of dynamic formulation model and three control techniques aiming to achieve accurate position control and improving dynamic stability for Two-Link Flexible Manipulators (TLFMs). LQR controller is designed based on the linearized model of the TLFM; however, it is applied on both linearized and nonlinear models. In addition to LQR, Backstepping and Sliding mode controllers are designed as nonlinear control approaches and applied on both the nonlinear model of the TLFM and the physical system. The three developed control techniques are tested through simulation based on the developed dynamic formulation model using MATLAB/SIMULINK. Stability and performance analysis were conducted and tuned to obtain the best results. Then, the performance and stability results obtained through simulation are compared. Finally, the developed control techniques were implemented and analyzed on the 2-DOF Serial Flexible Link Robot experimental system from Quanser and the results are illustrated and compared with that obtained through simulation

Performance analysis of modified asymmetrically-clipped optical orthogonal frequency-division multiplexing systems

A modification to the Asymmetrically-Clipped Optical Orthogonal Frequency-Division Multiplexing (ACO-OFDM) technique is proposed through unipolar encoding. A performance analysis of the Bit Error Rate (BER) is developed and Monte Carlo simulations are carried out to verify the analysis. Results are compared to that of the corresponding ACO-OFDM system under the same bit energy and transmission rate; an improvement of 1 dB is obtained at a BER of 10-4. In addition, the performance of the proposed system in the presence of atmospheric turbulence is investigated using single-input multiple-output (SIMO) configuration and its performance under that environment is compared to that of ACO-OFDM. Energy improvements of 4 dB and 2.2 dB are obtained at a BER of 10-4 for SIMO systems of 1 and 2 photodetectors at the receiver for the case of strong turbulence, respectively

A decision support system for the re-equilibrium of PPP contracts

Public Private Partnership (PPP) contracts tend to have longer contract durations compared to other conventional procurement methods. Due to their prolonged nature, PPP contracts are extremely prone to contract renegotiation along their lifecycles in comparison to other forms of contracts with shorter durations. The common outcomes of the renegotiation process may include: increasing the service charges, increasing the concession period, or paying a lump sum amount to the party of concern in order to maintain a fixed rate of return and keep the return on equity constant. In this research, a framework is developed in order to calculate the renegotiation process outcomes and facilitate the decision making process of choosing the optimum scenario that preserves the rights and the interests of all the stakeholders. This is done using a weighted sum model to calculate the weights and ranks of a number of factors influencing the stakeholders\u27 decisions. A Decision Support System (DSS) is developed with the aid of Microsoft Excel 2013, Visual Basic for Applications (VBA) programming language, and the Precision Tree 5.5 for Excel add-in. The data for the model is obtained from a case study of a wastewater treatment plant in Egypt. The results obtained from the model are close to the ones obtained from the Independent Financial Expert (IFE) of the wastewater treatment plant

Indications, Creation, and Complications of Colostomy in Neonates: Single Tertiary Center Experience Over Three Years

Background: The congenital anomalies that indicate colostomies in neonates at any tertiary paediatric surgery centre are Hirschsprung’s disease, anorectal anomalies, and colonic atresia and they constitute the main bulk of colostomy workloads. Objective: In this study, we aimed to evaluate the indications, site of creation, type of colostomy, and complications of colostomy in new-born in the last three years in a single tertiary center. Patients and Methods: This study was a retrospective cohort study that was carried out in the Paediatric Surgery Department, Tanta University Hospital, Egypt to evaluate the indications, site of creation, types of colostomies, and complications of colostomy in new-born over three years from March 2018 to March 2021. Results: High anorectal malformations (90%) and Hirschsprung’s disease (5%) were the most common causes of creation of neonatal colostomy. Out of 120 neonates, 71 (59 %) patients were males, and 49 (41 %) patients were females. The gestational age ranged between 35 and 40 weeks with a mean of 37.55 ± 1.43 weeks (mean ± SD). Complications of colostomy were seen in 38 (31.6%) neonates. Most common complications were skin excoriation in 22 (18 %) patients, stomal prolapse in 5 (4%) patients, bleeding from stoma site in 4 (3%) cases, wound infection in 3 (2.5%) cases, parastomal hernia in 2 (1.6%) patients, and dehiscence and stomal stenosis in one (0.8%) patient for each. Conclusions: Expert paediatric surgeons should perform or assist in colostomy creation operations in neonates and should pay close attention to proper choice of the site of colostomy with early management of complications and early closure of the colostomy

Model for the Automated Generation of Optimized Work Packages in Results-Based-Finance Mega Sanitation Projects

The sanitation sector is one of the critical sectors in any country. The lack of proper sanitation systems causes many environmental hazards that threaten people’s health and well-being. In many developing countries, the sanitation sector constitutes a significant part of their strategic plans of reform. However, with the public treasury’s very limited budget, countries opt to major lending institutions for funds. “Results-Based-Finance” is a new funding mechanism used by many lending institutions. The mechanism has proven its efficiency in achieving the necessary reform in sanitation sectors. Due to the complexity of the funding tool, it is crucial to be able to decompose the project into smaller packages to be able to manage and control the project effectively. The objective of this dissertation is to reach an optimum packaging scheme that enables mega sanitation infrastructure projects to be successfully managed through better planning and cost control practices. The model aim shall be to minimize the amount of funds needed from the borrowing country through three options: by reducing the peak value of the negative cashflow curve, by normalizing the negative cashflow curve, or by a combination of the previous two objectives. With the aid of Unified Modelling Language (UML), an algorithm is developed to map the logic behind the model suggested with detailed illustrations of its different modules. Object-oriented processes and operations are modeled using various diagrams of the language, which automatically generate the optimum packaging combination. The packaging model is then implemented via a number of computer-aided programs. Microsoft Excel is used for calculation purposes. Visual Basic for Applications (VBA) programming language is used to make the model user-friendly for non-engineering stakeholders. Palisade\u27s Decision Tools Suite is used for the genetic algorithm optimization process. In order to verify the model, different approaches have been used, which include system checks to minimize programming errors. Moreover, a sensitivity analysis module has been designed with the aid of Top Rank software in order to ensure the flexibility and the capabilities of the constructed model. After the model verification is conducted, the model shall be validated using data from a case study of a mega sanitation results-based financed project located in Egypt. The project is achieved through the World Bank and aims to strengthen the Egyptian Institutions for better service delivery by providing incentives. The project worth is 550 Million USD. The ability of the model to plot the optimization process and the suggested outputs is proven feasible. The model output is not only the content of the packages but also a complete managing plan which demonstrates much useful information to the decision-makers and government officials. Moreover, the model has reduced the peak value of the negative cashflow curve by 18.7 percent, normalized the negative cashflow curve by 5.4 percent, and the model has reduced the funding gap in general by 8.9 percent

Preterm with appendicular abscess and subcapsular liver haematoma: an unreported association

Neonatal appendicitis is a rare yet serious condition. Known reported associations are Hirschsprung’s disease, necrotising enterocolitis (NEC) and cystic fibrosis. The occurrence of subcapsular liver haematoma in preterm neonates can be life threatening. We present an unreported association of these two serious conditions in a preterm infant with appendicular abscess and subcapsular liver haematoma. She presented with sepsis, enlarged liver and tender right iliac fossa mass. Laparotomy was performed for possible complicated NEC. Intraoperatively, there was an appendicular abscess with a small subcapsular liver haematoma and no evidence of NEC. Appendectomy and peritoneal toilet were performed. She had a stormy postoperative period due to sepsis, thrombocytopaenia and expansion of her liver haematoma. The pathology of her appendix was in keeping with appendicitis, with no evidence of NEC. Her liver haematoma gradually resolved. Suction rectal biopsy showed normal ganglia. She was discharged after 7 weeks and remained well since then.Keywords: hematoma, liver, neonatal appendicitis, preterm, subcapsula

Influence of the Flexible Liposomes on the Skin Deposition of a Hydrophilic Model Drug, Carboxyfluorescein: Dependency on Their Composition

This study focuses on the effect of different flexible liposomes containing sodium cholate, Tween 80, or cineol on skin deposition of carboxyfluorescein (CF). Size distribution, morphology, zeta potential, and stability of the prepared vesicles were evaluated. The influence of these systems on the skin deposition of CF utilizing rat skin as membrane model was investigated. Results showed that all of the investigated liposomes had almost spherical shapes with low polydispersity (PDI < 0.3) and particles size range from 83 to 175 nm. All liposomal formulations exhibited negative zeta potential, good drug entrapment efficiency, and stability. In vitro skin deposition data showed that flexible liposomes gave significant deposition of CF on the skin compared to conventional liposomes and drug solutions. This study revealed that flexible liposomes, containing cineole, were able to deliver higher amount of CF suggesting that the hydrophilic drugs delivery to the skin was strictly correlated to the vesicle composition

Hyperhidrosis in children and review of its current evidence-based management

Hyperhidrosis (HH) is excessive sweating that usually interferes with the patient’s social life. In more than 80% of the cases, the symptoms start in childhood. Early detection and management can significantly improve the patient’s quality of life; however, HH remains widely underdiagnosed and undertreated, particularly among children. Many patients do not realize that they have a treatable condition and reports have shown that only 38% of the patients had discussed their condition with a healthcare  professional. The aim of this article was to improve awareness on the significant sequel of HH in children and highlight its effects on their quality of life and various available treatment options.Keywords: hyperhidrosis, medical treatment, paediatric, sympathectomy, thoracoscop