On-orbit assembly using superquadric potential fields

The autonomous on-orbit assembly of a large space structure is presented using a method based on superquadric artificial potential fields. The final configuration of the elements which form the structure is represented as the minimum of some attractive potential field. Each element of the structure is then considered as presenting an obstacle to the others using a superquadric potential field attached to the body axes of the element. A controller is developed which ensures that the global potential field decreases monotonically during the assembly process. An error quaternion representation is used to define both the attractive and superquadric obstacle potentials allowing the final configuration of the elements to be defined through both relative position and orientation. Through the use of superquadric potentials, a wide range of geometric objects can be represented using a common formalism, while collision avoidance can make use of both translational and rotation maneuvers to reduce total maneuver cost for the assembly process

Removal of some of priority organic pollutants (POPs) in conventionally treated wastewater

The occurrence, the fate and the removal of persistent organicpollutants (POPs) during the conventional treatment processes were assessed and investigated in wastewater treatment plant (WWTP) of 10 th of Ramadan city in thisstudy. The POPs of interest were twelve Polychlorinatedbiphenyls (PCBs), nineteen Organochlorine pesticides (OCPs), and eighteen Polyaromatic hydrocarbons (PAHs) which were measured at three sites along WWTP (Raw,Primary sedimentation effluent, final effluent). PCBs, OCPs and PAHs were represented persistent organic pollutants(POPs) in environment. PCBs were detected in higher concentration in raw samples due to their uses in industry. DDTand its metabolites were found in different frequencies and concentration. The removal percentages throughout the whole treatment process of individual POPs ranged from31 % to 98 %

Surgical Versus non Surgical Techniques for Punctal Occlusion as Alternative Methods for Treatment of Dry-eye in Dogs

The aim of the study was to describe three alternative methods for treatment of dry-eye in dogs and to determine the most appropriate method for clinical application. These treatments were include, surgical punctal occlusion and non-surgical temporary occlusion using silicon plugs and butyl-cyanoacrylate adhesive solution. It was carried out in two stages, stage I: to evaluate the efficacy of the three techniques in 12 normal dogs, which allocated into three equal groups as follows, silicon plugs (G1), butyl-cyanoacrlate adhesive (G2) and surgical punctal occlusion (G3). Stage II: a clinical study in nine clinical cases affected with dry-eye. The upper and lower puncta were obstructed, and Schirmer tear test I (STTI) values and Jones test were performed before and after carrying out the occlusion technique. Each technique was evaluated twice weekly for 60 days (stage I) and 30 days (stage II). All techniques improved the results of STTI values comparing to their control groups, with persistency period 20-23 days (G1), 12-16 days (G2) and 60 days (G3). The study proved that surgical occlusion was highly successful as permanent method with minimal complications and would be the treatment of choice for unresponsive cases to medical treatment of dry-eye in dogs

Effect of prophylactic salpingectomy on ovarian function in premenopausal women in tertiary referral center

Background: Epithelial ovarian cancers (EOCs) are the most common cause of death from gynaecological malignancy. Serous ovarian carcinomas represent (68%) of Epithelial ovarian cancers, they are further divided into low-grade (type I) and high-grade (type II) serous ovarian carcinomas. There has been increasing evidence that fallopian tubes are considered the most important site of origin of pelvic high grade serous carcinoma. Salpingectomy is thought to be effective in reducing ovarian cancer risk in the future and prolonging average life expectancy, however, there are some concerns regarding ovarian function after elective salpingectomy in premenopausal women. The current study was carried out to assess the effect of salpingectomy on ovarian function in premenopausal women.Methods: 60 premenopausal cases were recruited and subjected to open abdominal hysterectomy without oophorectomy (for benign indications). Included cases were below 45 years, with documented active ovarian functions. Cases with genital malignancy, ovarian gross pathology and suspected or known ovarian failure were excluded. Cases were randomly allocated to one of two groups; group-A (where salpingectomy was performed), and group-B (where salpingectomy was not done). For all patients, ovarian functions were assessed prior operation, and at one and three months after operation using serum anti-Mullarian hormone (AMH) as well as early follicular antral follicular count (AFC), serum follicle stimulating hormone (FSH) and serum oestradiol (E2).Results: The mean pre-operative AFC, AMH, FSH, and E2 levels showed no significant changes after operation at one and three months postoperative follow up in both studied groups, denoting preserved ovarian function in both groups.Conclusions: Prophylactic salpingectomy is a safe and simple procedure that has no effect on ovarian reserve or function when performed in premenopausal women

Computed Tomographic Features of the Camel Nasal Myiasis

The purpose of this work was to describe the computed tomographic (CT) features of nasal myiasis in camel (Camelus dromedarius), which caused by the larvae of camel nasal botfly Cephalopina titillator. Twenty infested heads of emergency slaughtered camels and five normal heads were obtained for the study. The normal anatomical features of the nasal cavity in CT images were identical to their cross sections without any pathological changes. The most commonly encountered CT findings in the infested group were (1) unilateral-rounded foci of soft tissue or fluid opacity in the ventral nasal concha in 100 % of cases, the foci also found bilaterally in the ethmoidal labyrinth 20% and frontal sinuses 5%. (2) Kidney-shaped hypolucent foci were found unilaterally in the ventral bulla 20% (3) Specific pattern of lesions distribution, which tend to be localized in three levels, the caudal two thirds of the ventral nasal concha, the ethmoidal labyrinth and the frontal sinus. It was concluded that, CT may be useful in detecting intranasal pathological changes associated with Cephalopina larval infestation in camel

Comparison of Three Techniques for Arthrocentesis of the Carpal Joint in Dromedary Camels: A Prospective Study

The aim of this prospective study was to determine the appropriate approaches for arthrocentesis of the carpal joint in dromedary camels and to compare between these approaches with regard to their success rate, feasibility, accuracy and ease of performance. Twenty-two cadaveric camel forelimbs obtained from 11 camel cadavers, and 4 living camels (6 joints) underwent arthrocentesis for therapeutic and diagnostic purposes, were used in this study. For studying gross anatomy of the suggested approaches, 4 forelimbs were used. For CT anatomy 3 forelimbs (one/each technique) were scanned before and after injection of iodinated contrast medium. For in-vitro evaluation of the techniques 15 forelimbs were used (5/each technique). To test the ease of performance in the living camels, arthrocentesis of 6 joints in 4 camels was performed by a single operator while the animal sited in kneeling position (3 camels) and standing position (one camel). Based on the results, there were three feasible approaches for arthrocentesis of carpal joint in camel, the dorso-medial, dorso-lateral, and the lateral approaches. The dorso-medial approach was easily performed and more accurate than the other approaches. The dorso-medial approach was successful with accuracy index of 100% after the first attempts, whilst the dorso-lateral and the lateral approaches have lower rates of success. The procedure was well tolerated in all camels

Practical Secrecy at the Physical Layer: Key Extraction Methods with Applications in Cognitive Radio

The broadcast nature of wireless communication imposes the risk of information leakage to adversarial or unauthorized receivers. Therefore, information security between intended users remains a challenging issue. Currently, wireless security relies on cryptographic techniques and protocols that lie at the upper layers of the wireless network. One main drawback of these existing techniques is the necessity of a complex key management scheme in the case of symmetric ciphers and high computational complexity in the case of asymmetric ciphers. On the other hand, physical layer security has attracted significant interest from the research community due to its potential to generate information-theoretic secure keys. In addition, since the vast majority of physical layer security techniques exploit the inherent randomness of the communication channel, key exchange is no longer mandatory. However, additive white Gaussian noise, interference, channel estimation errors and the fact that communicating transceivers employ different radio frequency (RF) chains are among the reasons that limit utilization of secret key generation (SKG) algorithms to high signal to noise ratio levels. The scope of this dissertation is to design novel secret key generation algorithms to overcome this main drawback. In particular, we design a channel based SKG algorithm that increases the dynamic range of the key generation system. In addition, we design an algorithm that exploits angle of arrival (AoA) as a common source of randomness to generate the secret key. Existing AoA estimation systems either have high hardware and computation complexities or low performance, which hinder their incorporation within the context of SKG. To overcome this challenge, we design a novel high performance yet simple and efficient AoA estimation system that fits the objective of collecting sequences of AoAs for SKG. Cognitive radio networks (CRNs) are designed to increase spectrum usage efficiency by allowing secondary users (SUs) to exploit spectrum slots that are unused by the spectrum owners, i.e., primary users (PUs). Hence, spectrum sensing (SS) is essential in any CRN. CRNs can work both in opportunistic (interweaved) as well as overlay and/or underlay (limited interference) fashions. CRNs typically operate at low SNR levels, particularly, to support overlay/underlay operations. Similar to other wireless networks, CRNs are susceptible to various physical layer security attacks including spectrum sensing data falsification and eavesdropping. In addition to the generalized SKG methods provided in this thesis and due to the peculiarity of CRNs, we further provide a specific method of SKG for CRNs. After studying, developing and implementing several SS techniques, we design an SKG algorithm that exploits SS data. Our algorithm does not interrupt the SS operation and does not require additional time to generate the secret key. Therefore, it is suitable for CRNs