1,786 research outputs found

    On-orbit assembly using superquadric potential fields

    Get PDF
    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

    Design of Adiabatic MTJ-CMOS Hybrid Circuits

    Full text link
    Low-power designs are a necessity with the increasing demand of portable devices which are battery operated. In many of such devices the operational speed is not as important as battery life. Logic-in-memory structures using nano-devices and adiabatic designs are two methods to reduce the static and dynamic power consumption respectively. Magnetic tunnel junction (MTJ) is an emerging technology which has many advantages when used in logic-in-memory structures in conjunction with CMOS. In this paper, we introduce a novel adiabatic hybrid MTJ/CMOS structure which is used to design AND/NAND, XOR/XNOR and 1-bit full adder circuits. We simulate the designs using HSPICE with 32nm CMOS technology and compared it with a non-adiabatic hybrid MTJ/CMOS circuits. The proposed adiabatic MTJ/CMOS full adder design has more than 7 times lower power consumtion compared to the previous MTJ/CMOS full adder

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

    Get PDF
    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

    Get PDF
    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

    A Study on Mass Spectrometry of Methylated [60] Fullerenes Using the “In-beam” Electron Impact Technique

    Get PDF
    Mass spectra of the methylated [60]fullerenes were obtained by EI mass spectrometry using “desorption” or “in-beam” technique. The mass spectra of the methylated fullerenes, C60Men, have the molecular ion peak M+ indicating that the product is stable under the MS (EI) conditions. The appearance of an intense peak at m/z 360 was assigned to the formation of fullerene dication C60++. The remaining peaks were assigned to successive loss of methyl groups from molecular monocation and dication

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

    Get PDF
    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

    Cordylobia Anthropophaga: Furuncular Myiasis in a Family of 3

    Get PDF
    Cutaneous myiasis due to infestation by the larva of Cordylobia anthropophaga is an underreported occurrence. Awareness is important to avoid misrecognition or delay in diagnosis. We describe a family of three with cutaneous myiasis caused by the African Tumbu fly (Cordylobia anthropophaga) presenting as multiple abscesses, demonstrating the need for a detailed travel history in such a presentation. The nature of the lesions, the life cycle and treatment modalities are discussed. Cutaneous myiasis requires an awareness of its clinical features specifically in patients presenting with furuncular skin lesions who live within endemic areas or persons returning from such areas. Diagnosis is mainly clinical and lesions heal well after the extraction of the larvae. Good personal hygiene including ironing of clothes is crucial in controlling C. anthropophaga infestation.Key Words: Myiasis, Furuncular, Cordylobia anthropophag

    Remifentanil vs dexmedetomidine for severely preeclamptic parturients scheduled for cesarean section under general anesthesia: A randomized controlled trial

    Get PDF
    AbstractObjectivesTo compare the effect of remifentanil vs dexmedetomidine on hemodynamic response of noxious stimuli and neonatal outcome in preeclamptic parturient underwent C.S. under G.A.MethodsThis blinded, prospective, randomized trial included 50 preeclamptic parturients underwent C.S under G.A., randomized into two equal groups [25 patients each]: group R [remifentanil]: received 1ÎĽg/kg loading and 0.05ÎĽg/kg/min infusion doses and group D [dexmedetomidine] received 1/kg loading and 0.2ÎĽg/kg/h infusion doses. Maternal MAP and HR were assessed before medication (T0), just after induction of GA (TI), just after intubation (TT), two minutes after intubation (TT2), just after skin incision (TS), two minutes after skin incision (TS2), just after delivery of the baby (TD), and at the end of operation (TE). Time between induction and fetal delivery (I-D interval), time between incision of the uterus and delivery (U-D interval), and time between stop of the infusion of the tested drugs and delivery (D-D interval) were recorded. Neonatal Apgar score was recorded at 1 and 5min and the need for resuscitative measures.ResultsMaternal MAP and HR in group R were statistically lower at (TI), (TT), (TT2), (TS) and (TS2). Neonatal Apgar score was statistically lower in group R with higher incidence for tactile stimulation.ConclusionBoth remifentanil and dexmedetomidine were effective on blunting the pressor response to noxious stimuli in severely preeclamptic parturients. While remifentanil was marginally more effective in suppressing the pressor response, dexmedetomidine was safer for the neonates
    • …
    corecore