Sonic Boom Mitigation through Shock Wave Dispersion

Lately, the interest for passenger space planes, supersonic passenger aircraft, and supersonic business jets has greatly increased. In order to mitigate the sonic boom effects at ground level, some aerospace companies proposed airplanes that have a very small transversal fuselage section or that have a curved (“shaped”) fuselage. Obviously, shaping the fuselage leads to the increase of dynamic drag and manufacturing cost. Reducing the fuselage transverse section leads to reducing the useful volume inside fuselage and increases the landing distance of aircraft. The solution presented in this chapter shows that it is theoretically and technologically possible as the shock wave to be dispersed through mechanical or electrical means. The shock wave is in fact a stationary effect generated by the move of aircraft with constant speed relatively to surrounding air. If this feature is in a way or another canceled, the shock wave is dispersing. Due to dispersion of the shock wave the ‘N’ wave at the ground is tens of times larger and the sonic boom is correspondingly lower. The shock wave dispersion system of the future could be mechanical or electrical is activated only when the supersonic aircraft/space plane is flying horizontally over community

Experimental Investigations on the Possibility to Apply the Corrugated Sheet Metal Used in the Past with Junkers Aircraft to Reduce Noise for Future European Aircraft. Other Noise Reduction Experiments for Future European Aircraft

This paper shows that corrugated skin used in the past with Junkers aircraft to increase the fuselage and wing rigidity can lead to noise reduction for future European aircraft. If the pressure side of wing which is placed above the engine is corrugated, the jet noise reflected by wing will be scattered. This way, the diffuse acoustic field has a lower intensity at ground level and correspondingly, a lower impact on community. Similarly, it is shown that if the underside of fuselage is corrugated, the noise emitted by the nose landing-gear and main landing-gear is also scattered. The existence of this effect is demonstrated by some recent measurements done inside auto-tunnels covered inside with corrugated sheet metal which indicated a reduction of maximum noise level by up to 30%. Some experiments done by the authors at low scale on an Airbus A380 wing model (scale 1:375) showed that the jet-noise reflected by the corrugated skin of wing is reduced by 4 dB in the near field. Reintroducing corrugated skin in the manufacturing process of modern aircraft is beneficial because, on the one hand, it reduces the jet and the landing-gear noise discomfort and, on the other hand, it permits manufacturing stronger frames for passenger aircraft/airliners

Our initial experience with ventriculo-epiplooic shunt in treatment of hydrocephalus in two centers

Introduction Hydrocephalus represents impairment in cerebrospinal fluid (CSF) dynamics. If the treatment of hydrocephalus is considered difficult, the repeated revisions of ventriculo-peritoneal (VP) shunts are even more challenging. Objective The aim of this article is to evaluate the efficiency of ventriculo-epiplooic (VEp) shunt as a feasible alternative in hydrocephalic patients. Material and methods A technical modification regarding the insertion of peritoneal catheter was imagined: midline laparotomy 8–10cm long was performed in order to open the peritoneal cavity; the great omentum was dissected between its two layers; we placed the distal end of the catheter between the two epiplooic layers; a fenestration of 4cm in diameter into the visceral layer was also performed. A retrospective study of medical records of 15 consecutive patients with hydrocephalus treated with VEp shunt is also presented. Results Between 2008 and 2014 we performed VEp shunt in 15 patients: 5 with congenital hydrocephalus, 8 with secondary hydrocephalus and 2 with normal pressure hydrocephalus. There were 7 men and 8 women. VEp shunt was performed in 13 patients with multiple distal shunt failures and in 2 patients, with history of abdominal surgery, as de novo extracranial drainage procedure. The outcome was favorable in all cases, with no significant postoperative complications. Conclusions VEp shunt is a new, safe and efficient surgical technique for the treatment of hydrocephalus. VEp shunt is indicated in patients with history of recurrent distal shunt failures, and in patients with history of open abdominal surgery and high risk for developing abdominal complications

Biocompatibility Study of CoCrMoSi k Original Alloy Variants

The study follow the improvement of properties of cobalt base alloys, used in medical applications. This scope targeted the obtaining of alloys with friendly biological interactions to human body. If the original variants of CoCrMoSi k (k = 4, 5, 6, 7) alloys don't subjected to the criteria of biological acceptance from animal body, these don't be placed in live body, indifferent the adequacy of the biomaterials properties. Realization of the original alloy variants must consider and the possibility to appear the base pathophysiological phenomena, with determine or not their safety on long time (generate of thrombosis, inflammation, infection and / or inducing and causing neoplasms)

Introduction to Metallic Biomaterials

The paper presents a bibliographic study about the metallic biomaterials, synthesizing the aspects related to properties, applicability, obtaining methods. Biomaterials can be used as medical devices, implants and prostheses. The metallic biomaterials are classified, by chemical composition and structure, in: pure technical metals, metallic alloys and composites with metallic matrix. The material quality of an implant must respect the following criteria: biochemical criteria and biomechanical ones. According to the biochemical criterion, the applicability of a material is determined by its biocompatibility, and from the biochemical criteria, it is determined by the fatigue resistance, the most important parameter, but not the only one

New Trends in Bioactive Glasses for Bone Tissue: A Review

Bioactive glasses are very attractive materials, used for tissue engineering materials, usually to fill and restore bone defects. This category of biomaterials, show considerable potential for orthopaedic surgery because they can promote bone tissue regeneration. Many trace elements have been incorporated in the glass network, an example is metallic glasses to obtain the desired properties. Because of tolerable mechanical properties, and because they are able to bond to living bone and stimulate its regeneration, this bioactive glasses have a particular interest and are in a continuous research and improvement. The chapter presents the history of bioactive glasses, classification, include a summary of common fabrication methods, applications, surface coatings, applications and future trends in relation to human bone. This review highlight new trends and areas of future research for bioactive glasses

ASSESSING THE POSSIBILITIES OF FILLING THE GAP BETWEEN ROMANIA AND THE EU IN THE RDI FIELD

In the specialised literature there are several established models and methods for measuring the time required to fill the gap between various systems, by assessing the rate of development required to reach a certain reference level in a determined period of time. These models are known as “catching-up models”. The purpose of this study is the assessment, based on such models, of the pace required to fill the gap between Romania and the EU in the R&D field as well as of the factors that condition the pace required to achieve convergence with EU-25 average.catching-up models, gap filling, RDI public private funding