Perforated exit regions for the reduction of micro-pressure waves from tunnels

The authors are grateful to the following bodies that provided financial support for the project: (i) China Scholarship Council (20117 00029), (ii) National Natural Science Foundation of China (Grant no. U1334201) and (iii) UK Engineering and Physical Sciences Research Council (Grant no. EP/G069441/1).

Perforated exit regions for the reduction of micro-pressure waves from tunnels

The authors are grateful to the following bodies that provided financial support for the project: (i) China Scholarship Council (20117 00029), (ii) National Natural Science Foundation of China (Grant no. U1334201) and (iii) UK Engineering and Physical Sciences Research Council (Grant no. EP/G069441/1).

Investigations on micro-blast wave assisted metal foil forming for biomedical applications

The deformation dynamics of metal foils (<0.25 mm thick) subjected to micro-blast wave are presented in this paper. The energy of micro-blast wave emanating from the open end of a polymer tube is used to deliver micro-particles for bio-medical applications. In these experiments metal foils are used to transfer the energy of the micro-blast wave to the micro-particles. Using cubic root scaling law the over pressure of the blast wave at the open end of the polymer tube is estimated and using this peak plate over pressure is estimated. The finite element analysis is used to estimate the velocity profile of the deforming metal foils. The finite element analysis results are compared with experimental results for the maximum deformation and deformed shape. Based on the deformation velocity, metal foil to be used for experiments is selected. Among the materials investigated 0.1 mm thick brass foil has the maximum velocity of 205 m/s and is used in the experiments. It is found from finite element analysis that the particles deposited within a radius of 0.5 mm will leave the foil with nearly equal velocity (error < 5%). The spray cone angle which is the angle of deviation of the path of particles from the axis of the polymer tube is also estimated and found to be less than 7 degrees up to a radius of 0.75 mm. Illustrative experiments are carried out to deliver micro particles (0.7 mu m diameter tungsten) into plant tissues. Particle penetration depth up to 460 mu m was achieved in ground tissue of potato tuber. (C) 2012 Elsevier Ltd. All rights reserved.

The micro-movie wave in a globalising China : adaptation, formalisation and commercialisation

While user-generated short online videos have existed since the emergence of video sharing sites in China, they have undergone a process of formalisation and commercialisation, culminating in the wave of micro-movies in recent years. By addressing the wider context of globalisation alongside relevant state policies and shifting viewing habits, this article analyses the local and global causes of this wave. It offers evidence that illustrates how online video service providers in China have adapted in a changing industry landscape as they negotiate state policies, advertiser interests and user preference. It then examines the production and distribution dynamics, where professional producers draw on social media, grassroots creativity and creative talents in regional markets. Finally, it discusses the cultural implications of this process in terms of both the nature and flow of creativity. Based on these analyses, the article also sheds light on the interplay between the state and the market in the context of globalisation and marketisation of media sectors, which becomes more complicated when the state-owned or controlled media enter the emerging market sectors.

Development of micro-shock wave assisted dry particle and fluid jet delivery system

Small quantity of energetic material coated on the inner wall of a polymer tube is proposed as a new method to generate micro-shock waves in the laboratory. These micro-shock waves have been harnessed to develop a novel method of delivering dry particle and liquid jet into the target. We have generated micro-shock waves with the help of reactive explosive compound high melting explosive (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine) and traces of aluminium] coated polymer tube, utilising 9 J of energy. The detonation process is initiated electrically from one end of the tube, while the micro-shock wave followed by the products of detonation escape from the open end of the polymer tube. The energy available at the open end of the polymer tube is used to accelerate tungsten micro-particles coated on the other side of the diaphragm or force a liquid jet out of a small cavity filled with the liquid. The micro-particles deposited on a thin metal diaphragm (typically 100-mu m thick) were accelerated to high velocity using micro-shock waves to penetrate the target. Tungsten particles of 0.7 mu m diameter have been successfully delivered into agarose gel targets of various strengths (0.6-1.0 %). The device has been tested by delivering micro-particles into potato tuber and Arachis hypogaea Linnaeus (ground nut) stem tissue. Along similar lines, liquid jets of diameter 200-250 mu m (methylene blue, water and oils) have been successfully delivered into agarose gel targets of various strengths. Successful vaccination against murine salmonellosis was demonstrated as a biological application of this device. The penetration depths achieved in the experimental targets are very encouraging to develop a future device for biological and biomedical applications.

Evaluation of mechanical losses in a linear motor pressure wave generator

A moving magnet linear motor compressor or pressure wave generator (PWG) of 2 cc swept volume with dual opposed piston configuration has been developed to operate miniature pulse tube coolers. Prelimnary experiments yielded only a no-load cold end temperature of 180 K. Auxiliary tests and the interpretation of detailed modeling of a PWG suggest that much of the PV power has been lost in the form of blow-by at piston seals due to large and non-optimum clearance seal gap between piston and cylinder. The results of experimental parameters simulated using Sage provide the optimum seal gap value for maximizing the delivered PV power.

Micro-shock wave assisted bacterial transformation

A gene is a unit of heredity in a living organism. It normally resides on a stretch of DNA that codes for a type of protein or for an RNA chain that has a function in the organism. All living things depend on genes, as they specify all proteins and functional RNA chains. Genes hold the information to build and maintain an organism’s cells and pass genetic traits to offspring. The gene has to be transferred to bacteria or eukaryotic cells for basic and applied molecular biology studies. Bacteria can uptake exogenous genetic material by three ways: conjugation, transduction and transformation. Genetic material is naturally transferred to bacteria in case of conjugation and transferred through bacteriophage in transduction. Transformation is the acquisition of exogenous genetic material through cell wall. The ability of bacteria of being transformed is called competency and those bacteria which have competency are competent cells. Divalent Calcium ions can make the bacteria competent and a heat shock can cause the bacteria to uptake DNA. But the heat shock method cannot be used for all the bacteria. In electroporation, a brief electric shock with an electric field of 10-20kV/cmmakes pores in the cell wall, facilitates the DNA to enter into the bacteria. Microprecipitates, microinjection, liposomes, and biological vectors are also used to transfer polar molecules like DNA into host cells.

Studies on an improved indigenous pressure wave generator and its testing with a pulse tube cooler

Earlier version of an indigenously developed Pressure Wave Generator (PWG) could not develop the necessary pressure ratio to satisfactorily operate a pulse tube cooler, largely due to high blow by losses in the piston cylinder seal gap and due to a few design deficiencies. Effect of different parameters like seal gap, piston diameter, piston stroke, moving mass and the piston back volume on the performance is studied analytically. Modifications were done to the PWG based on analysis and the performance is experimentally measured. A significant improvement in PWG performance is seen as a result of the modifications. The improved PWG is tested with the same pulse tube cooler but with different inertance tube configurations. A no load temperature of 130 K is achieved with an inertance tube configuration designed using Sage software. The delivered PV power is estimated to be 28.4 W which can produce a refrigeration of about 1 W at 80 K.

Remotely triggered micro-shock wave responsive drug delivery system for resolving diabetic wound infection and controlling blood sugar levels

A novel, micro-shock wave responsive spermidine and dextran sulfate microparticle was developed. Almost 90% of the drug release was observed when the particles were exposed to micro-shock waves 5 times. Micro-shock waves served two purposes; of releasing the antibiotic from the system and perhaps disrupting the S. aureus biofilm in the skin infection model. A combination of shock waves with ciprofloxacin loaded microparticles could completely cure the S. aureus infection lesion in a diabetic mouse model. As a proof of concept insulin release was triggered using micro-shock waves in diabetic mice to reduce the blood glucose level. Insulin release could be triggered for at least 3 days by exposing subcutaneously injected insulin loaded particles.

Wave Propagation Analysis in a Pressure-Wave-Refrigerator

Pressure wave refrigerators (PWR) refrigerate the gas through periodical expansion waves. Due to its simple structure and robustness, PWR may have many potential applications if the efficiency becomes competitive with existing alternative devices. In order to improve the efficiency, the characteristics of wave propagation in a PWR are studied by experiment, numerical simulation and theoretical analysis. Based on the experimental results and numerical simulation, a simplified model is suggested, which includes the assumptions of flux-equilibrium and conservation of the free energy. This allows the independent analysis of the operation parameters and design specifics. Furthermore, the optimum operation condition can be deduced. Some considerations to improve the PWR efficiency are also given.

Wave Propagation Analysis in a Pressure-Wave-Refrigerator

Pressure wave refrigerators (PWR) refrigerate the gas through periodical expansion waves. Due to its simple structure and robustness, PWR may have many potential applications if the efficiency becomes competitive with existing alternative devices. In order to improve the efficiency, the characteristics of wave propagation in a PWR are studied by experiment, numerical simulation and theoretical analysis. Based on the experimental results and numerical simulation, a simplified model is suggested, which includes the assumptions of flux-equilibrium and conservation of the free energy. This allows the independent analysis of the operation parameters and design specifics. Furthermore, the optimum operation condition can be deduced. Some considerations to improve the PWR efficiency are also given.

Particle Image Velocimetry Investigation of a finite amplitude pressure wave

Particle image velocimetry is used to study the motion of gas within a duct subject to the passage of a finite amplitude pressure wave. The wave is representative of the pressure waves found in the exhaust systems of internal combustion engines. Gas particles are accelerated from stationary to 150 m/s and then back to stationary in 8 ms. It is demonstrated that gas particles at the head of the wave travel at the same velocity across the duct cross section at a given point in time. Towards the tail of the wave viscous effects are plainly evident causing the flow profile to tend towards parabolic. However, the instantaneous mean particle velocity across the section is shown to match well with the velocity calculated from a corresponding measured pressure history using 1D gas dynamic theory. The measured pressure history at a point in the duct was acquired using a high speed pressure transducer of the type typically used for engine research in intake and exhaust systems. It is demonstrated that these are unable to follow the rapid changes in pressure accurately and that they are prone to resonate under certain circumstances.

On the Analytical Approach to Present Engineering Problems: Photovoltaic Systems Behavior, Wind Speed Sensors Performance, and High-Speed Train Pressure Wave Effects in Tunnels

At present, engineering problems required quite a sophisticated calculation means. However, analytical models still can prove to be a useful tool for engineers and scientists when dealing with complex physical phenomena. The mathematical models developed to analyze three different engineering problems: photovoltaic devices analysis; cup anemometer performance; and high-speed train pressure wave effects in tunnels are described. In all cases, the results are quite accurate when compared to testing measurements.