Simulating and Designing RF Transmitter for Small Satellites

This paper discusses the simulation and the design of an RF transmitter for small satellites operating in the commercial S- band (2.2 - 2.29 GHz) with a data rate of 8Mbps. In such systems, modelling frequency-dependent nonlinear characteristics of complex analog blocks and subsystems is critical for enabling efficient verification of mixed-signal system designs. In order to provide efficient and accurate simulation for the transmitter circuits, simple macromodels for weakly nonlinear mixer and power amplifier are used in the system simulation. Also, we introduce the noise in several circuits (frequency synthesizer, crystal oscillator, power amplifier, mixer,…) and we demonstrate their effect on the noise performance system. In the simulation we consider features of components and technologies commercially available

Kite Generator System Periodic Motion Planning Via Virtual Constraints

International audienceThis paper presents a new control strategy for Kite Generator System (KGS). The proposed feedback strategy is based on motion planning using the virtual constraint approach and ensures exponential orbital stability of the desired trajectory. The strategy is detailed, applied and tested via numerical simulations and showed good convergence to a desired periodic motion

Effect of stripe clearing on 4 grasses species and 2 broadleaves of caldenal

En la Región del Espinal, Distrito del Caldén, en la provincia de San Luis existe un fuerte proceso de agriculturización con la consecuente pérdida de remanentes de bosque nativo, peligro de conservación de especies nativas e invasión de especies exóticas. El objetivo del presente trabajo fue evaluar el efecto del desmonte en franjas sobre 6 especies del caldenal (4 gramíneas y 2 latifoliadas). El estudio se realizó en un campo a 15 km. al norte de la ciudad de Villa Mercedes (San Luis), sometido a un desmonte en franjas para uso agrícola en el año 2003. En 5 sitios ubicados en franjas remanentes de bosque nativo y 5 en bosque nativo sin desmonte, se trazaron transectas de 39 m de longitud, dirección NS y a lo largo de la misma se registraron las especies presentes en 14 unidades de muestreo de 1 m2. Los datos se analizaron utilizando IBM SPSS Statistics 19, mediante Métodos No Paramétricos, U de Mann-Whitney. El análisis estadístico mostró diferencias significativas (p<0.05) en Digitaria californica, Pappophorum pappiferum, Salsola kali y Cestrum parqui. El estudio demostró que el cultivo entre franjas de bosque nativo produjo un cambio en la frecuencia de poáceas nativas y de latifoliadas.In the region of “Espinal”, Calden Distrct in the province of San Luis there is a strong agriculturization process with the consequent loss of native forest remnants, conserving endangered native species and invasion of exotic species. The aim of this study was to evaluate the effect of the stripe clearing on 6 species of caldenal (4 grasses and 2 broa- dleaves). The study was conducted in a field 15 km to the north of the city of Villa Mercedes (San Luis), subjected to a strip-clearing for agricultural use, in the year 2003. On 5 sites into native forest remnants stripes and 5 into without clearing native forest, 39 m long tran- sects were laid, N-S direction, and along the same were recorded the presente species in 14 sampling units of 1 m2. Data were analyzed by IBM SPSS Statistics 19, through non- parametric methods, Mann-Whitney U. Statistical analysis showed significant differences (p <0.05) in Digitaria californica, Pappophorum pappiferum, Salsola kali and Cestrum par- qui. The study showed that the cultivation of native forest between stripes was a change in the frequency of native grasses and broadleaves.Fil: Ruiz, O. M.. Universidad Nacional de San Luis; Argentina;Fil: Luna, H. R.. Universidad Nacional de San Luis; Argentina;Fil: Bacha, Emmanuel Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - CONICET - San Luis; Argentina; Universidad Nacional de San Luis; Argentina;Fil: Pedranzani, H.. Universidad Nacional de San Luis; Argentina;Fil: Gabutti, E.G.. Universidad Nacional de San Luis; Argentina

Neonatal Tetanus Case Series: A Tale of Survival and Tragedy at St Paul Hospital Millennium Medical College, Addis Ababa, Ethiopia

Tigist Bacha,1 Mahlet Abayneh,2 Dawit Bekele Tefera3 1Division of Pediatric Emergency and Critical Care, Department of Pediatrics and Child Health St Paul Hospital Millennium Medical College, Addis Ababa, Ethiopia; 2Division of Neonatology Department of Pediatrics and Child Health St Paul Hospital Millennium Medical College, Addis Ababa, Ethiopia; 3Ohio State Global One Health LLC, Addis Ababa, EthiopiaCorrespondence: Dawit Bekele Tefera, Tel +251-912360352, Email [email protected]: Neonatal tetanus remains a significant threat in regions with limited healthcare access, despite being preventable through vaccination. The case-fatality rate of untreated neonatal tetanus is close to 100%. Even one case of neonatal tetanus regarded as a failure of the healthcare system, making it essential to remain mindful of this disease’s relevance to public health. Two cases of neonatal tetanus are presented, highlighting the severe consequences of the disease. One infant survived after ICU treatment, while the other succumbed despite medical intervention.Conclusion: These cases underscore the critical need for clean delivery practices and Tetanus anti-toxoid vaccination for women of reproductive age. Improving access to quality antenatal healthcare and promoting clean birth practices are essential in reducing the incidence of neonatal tetanus and preventing unnecessary deaths.Keywords: neonatal tetanus, home delivery, Ethiopi

ETUDE ELECTROCHIMIQUE DE L’INHIBITION DU PROCEDE D’ENTARTRAGE DANS UNE EAU DE MER

Calcareous scaling on domestic and industrial equipments generates severe problems and causes drastic economic loss. The use of several chemicals is a common technique to impede the scale deposition. The subject of this study is the inhibition of the scaling process. Thus, we have followed the coverage of a titanium electrode, in absence and in presence of two anti-scale products, using the chronoamperometry. The mineral scales were characterized by electrochemical impedance spectroscopy (EIS) and analyzed by electronic sweeping microscopy (ESM). It was found that 25 ppm of hydroxyl-2 méthyl-4 benzylphosponic acide (AHMBP) or of Diprochim anti-scale is sufficient to prevent electrodeposition. The efficiency of the two chemicals is comparable.L’entartrage des installations domestiques ou industrielles cause de sévères problèmes techniques et économiques. La technique la plus courante utilisée pour ralentir cette déposition consiste à utiliser divers inhibiteurs chimiques. L’objectif de cette étude rentre dans ce cadre. En effet, nous avons suivi par chronoampérométrie, l’évolution du recouvrement d’une électrode en titane, en absence et en présence de deux inhibiteurs d’entartrage. Les dépôts formés sont caractérisés par la spectroscopie d’impédance électrochimique (SIE) et analysés par microscopie électronique à balayage (MEB). 25 ppm de l’acide hydroxy-2 méthyl-4 benzylphosponique (AHMBP) ou de l’antitartre Diprochim suffisent pour ralentir considérablement le recouvrement de l’électrode. L’efficacité des deux inhibiteurs utilisés est comparable

Perventricular device closure of muscular ventricular septal defects on the beating heart: technique and results

AbstractObjectiveBoth surgical management and percutaneous device closure of muscular ventricular septal defects have drawbacks and limitations. This report describes our initial experience with intraoperative device closure of muscular ventricular septal defects without cardiopulmonary bypass in 6 consecutive patients.MethodsA median sternotomy or a subxiphoid minimally invasive incision was performed. Under continuous transesophageal echocardiographic guidance, the right ventricle free wall was punctured, and a wire was introduced across the largest defect. The Amplatzer (AGA Medical Corporation, Golden Valley, Minn) muscular ventricular septal defect occluding device (a self-expandable double-disk device) was used. An introducer sheath was fed over the wire, with the sheath tip positioned in the left ventricle cavity. The device was then advanced inside the sheath and deployed by retracting the sheath. Associated cardiac lesions, if any, can then be repaired during cardiopulmonary bypass. A similar technique can also be applied for periatrial closure of complex atrial septal defects.ResultsThe initial 6 patients are presented. Cardiopulmonary bypass was not needed in any patient for placement of the device and needed in 4 patients for repair of concomitant malformations only (double-outlet right ventricle, aortic arch hypoplasia, pulmonary artery band removal). No complications from using this technique occurred. Discharge echocardiograms showed no significant shunting across the ventricular septum.ConclusionsPerventricular closure of multiple muscular ventricular septal defects is safe and effective. We believe that this could become the treatment of choice for any infant with muscular ventricular septal defects or any child with muscular ventricular septal defect and associated cardiac defects