Instabilities of a liquid film flowing down an inclined porous plane

The problem of a film flowing down an inclined porous layer is considered. The fully developed basic flow is driven by gravitation. A careful linear instability analysis is carried out. We use Darcy's law to describe the porous layer and solve the coupling equations of the fluid and the porous medium rather than the decoupled equations of the one-sided model used in previous works. The eigenvalue problem is solved by means of a Chebyshev collocation method. We compare the instability of the two-sided model with the results of the one-sided model. The result reveals a porous mode instability which is completely neglected in previous works. For a falling film on an inclined porous plane there are three instability modes, i.e., the surface mode, the shear mode, and the porous mode. We also study the influences of the depth ratio d, the Darcy number delta, and the Beavers-Joseph coefficient alpha(BJ) on the instability of the system.

On the diffraction of acoustic waves by a quarter-plane

This paper follows the work of A.V. Shanin on diffraction by an ideal quarter-plane. Shanin's theory, based on embedding formulae, the acoustic uniqueness theorem and spherical edge Green's functions, leads to three modified Smyshlyaev formulae, which partially solve the far-field problem of scattering of an incident plane wave by a quarter-plane in the Dirichlet case. In this paper, we present similar formulae in the Neumann case, and describe a numerical method allowing a fast computation of the diffraction coefficient using Shanin's third modified Smyshlyaev formula. The method requires knowledge of the eigenvalues of the Laplace-Beltrami operator on the unit sphere with a cut, and we also describe a way of computing these eigenvalues. Numerical results are given for different directions of incident plane wave in the Dirichlet and the Neumann cases, emphasising the superiority of the third modified Smyshlyaev formula over the other two. © 2011 Elsevier B.V.

Anti-counterfeiting and supply chain security

Counterfeit trade developed into a severe problem for many industries. While established security features such as holograms, micro printings or chemical markers do not seem to efficiently avert trade in illicit imitation products, RFID technology, with its potential to automate product authentications, may become a powerful tool to enhance brand and product protection. The following contribution contains an overview on the implication of product counterfeiting on affected companies, provides a starting point for a structured requirements definition for RFID-based anti-counterfeiting systems, and outlines several principal solution approaches that are discussed in greater detail in the subsequent chapters. © 2008 Springer-Verlag Berlin Heidelberg.

Non-modal instabilities of two-dimensional disturbances in plane Couette flow of a power-law fluid

Instabilities of fluid flows have traditionally been investigated by normal mode analysis, i.e. by linearizing the equations of flow and testing for unstable eigenvalues of the linearized problem. However, the results of eigenvalue analysis agree poorly in many cases with experiments, especially for shear flows. In this paper we study the instabilities of two-dimensional Couette flow of a polymeric fluid in the framework of non-modal stability theory rather than normal mode analysis. A power-law model is used to describe the polymeric liquid. We focus on the response to external excitations and initial conditions by examining the pseudospectra structures and the transient energy growths. For both Newtonian and non-Newtonian flows, the results show that there can be a rather large transient growth even though the linear operator of Couette flow has no unstable eigenvalue. The effects of non-Newtonian viscosity on the transient behaviors are examined in this study. The results show that the "shear-thinning/shear-thickening" effect increases/decreases the amplitude of responses to external excitations and initial conditions. (C) 2010 Elsevier B.V. All rights reserved.

Instabilities and transient behaviors of a liquid film flowing down a porous inclined plane

The nonmodal linear stability of a falling film over a porous inclined plane has been investigated. The base flow is driven by gravity. We use Darcy's law to describe the flow in the porous medium. A simplified one-sided model is used to describe the fluid flow. In this model, the influence of the porous layer on the flow in the film can be identified by a parameter beta. The instabilities of a falling film have traditionally been investigated by linearizing the governing equations and testing for unstable eigenvalues of the linearized problem. However, the results of eigenvalue analysis agree poorly in many cases with experiments, especially for shear flows. In the present paper, we have studied the linear stability of three-dimensional disturbances using the nonmodal stability theory. Particular attentions are paid to the transient behavior rather than the long time behavior of eigenmodes predicted by traditional normal mode analysis. The transient behaviors of the response to external excitations and the response to initial conditions are studied by examining the pseudospectral structures and the energy growth function G(t) Before we study the nonmodal stability of the system, we extend the results of long-wave analysis in previous works by examining the linear stabilities for streamwise and spanwise disturbances. Results show that the critical conditions of both the surface mode and the shear mode instabilities are dependent on beta for streamwise disturbances. However, the spanwise disturbances have no unstable eigenvalue. 2010 American Institute of Physics. [doi:10.1063/1.3455503]

叠前深度偏移速度模型的建立方法研究

Seismic exploration is the main tools of exploration for petroleum. as the society needs more petroleum and the level of exploration is going up, the exploration in the area of complex geology construction is the main task in oil industry, so the seismic prestack depth migration appeared, it has good ability for complex construction imaging. Its result depends on the velocity model strongly. So for seismic prestack depth migration has become the main research area. In this thesis the difference in seismic prestack depth migration between our country and the abroad has been analyzed in system. the tomographical method with no layer velocity model, the residual curve velocity analysical method based on velocity model and the deleting method in pre-processing have been developed. In the thesis, the tomographysical method in velocity analysis is been analyzed at first. It characterized with perfection in theory and diffculity in application. This method use the picked first arrivial, compare the difference between the picked first arrival and the calculated arrival in theory velocity model, and then anti-projected the difference along the ray path to get the new velocity model. This method only has the hypothesis of high frequency, no other hypothesis. So it is very effective and has high efficiency. But this method has default still. The picking of first arrival is difficult in the prestack data. The reasons are the ratio of signal to noise is very low and many other event cross each other in prestack data. These phenomenon appear strongly in the complex geology construction area. Based on these a new tomophysical methos in velocity analysis with no layer velocity model is been developed. The aim is to solve the picking problem. It do not need picking the event time contiunely. You can picking in random depending on the reliability. This methos not only need the pick time as the routine tomographysical mehtod, but also the slope of event. In this methos we use the high slope analysis method to improve the precision of picking. In addition we also make research on the residual curve velocity analysis and find that its application is not good and the efficiency is low. The reasons is that the hypothesis is rigid and it is a local optimizing method, it can solve seismic velocity problem in the area with laterical strong velocity variation. A new method is developed to improve the precision of velocity model building . So far the pattern of seismic prestack depth migration is the same as it aborad. Before the work of velocity building the original seismic data must been corrected on a datum plane, and then to make the prestack depth migration work. As we know the successful example is in Mexico bay. It characterized with the simple surface layer construction, the pre-precessing is very simple and its precision is very high. But in our country the main seismic work is in land, the surface layer is very complex, in some area the error of pre-precessing is big, it affect the velocity building. So based on this a new method is developed to delete the per-precessing error and improve the precision of velocity model building. Our main work is, (1) developing a effective tomographical velocity building method with no layer velocity model. (2) a new high resolution slope analysis method is developed. (3) developing a global optimized residual curve velocity buliding method based on velocity model. (4) a effective method of deleting the pre-precessing error is developing. All the method as listed above has been ceritified by the theorical calculation and the actual seismic data.

The Synthesis of Stable Grasps in the Plane

This paper addresses the problem of synthesizing stable grasps on arbitrary planar polygons. Each finger is a virtual spring whose stiffnes and compression can be programmed. The contacts between the finger tips and the object are point contacts without friction. We prove that all force-closure grasps can be made stable, and it costs 0(n) time to synthesize a set of n virtual springs such that a given force closure grasp is stable. We can also choose the compliance center and the stiffness matrix of the grasp, and so choose the compliant behavior of the grasped object about its equilibrium. The planning and execution of grasps and assembly operations become easier and less sensitive to errors.

Problems of maximal mean resistance on the plane

Plakhov, A.Y.; Gouveia, P.D.F., (2007) 'Problems of maximal mean resistance on the plane', Nonlinearity 20(9) pp.2271-2287 RAE2008

Characterising novel anti-biofilm targets for the treatment of chronic Pseudomonas aeruginosa infection in the cystic fibrosis lung

The global rise in antibiotic resistance is a significant problem facing healthcare professionals. In particular within the cystic fibrosis (CF) lung, bacteria can establish chronic infection and resistance to a wide array of antibiotic therapies. One of the principle pathogens associated with chronic infection in the CF lung is Pseudomonas aeruginosa. P. aeruginosa can establish chronic infection in the CF lung partly through the use of the biofilm mode of growth. This biofilm mode of growth offers a considerable degree of protection from a wide variety of challenges such as the host immune system or antibiotic therapy. The threat posed by the emergence of chronic pathogens is prompting the development of next generation antimicrobials. The biofilm mode of growth is often central to the establishment of chronic infection and the development of antibiotic resistance. Thus, targeting biofilm formation has emerged as one of the principle strategies for the development of next generation antimicrobials. In this thesis two separate approaches were used to identify potential anti - biofilm targets. The first strategy focused on the identification of novel genes with a role in a biofilm formation. High throughput screening identified almost 300 genes which had a role in biofilm formation. A number of these genes were characterised at a phenotypic and a molecular level. The second strategy focused on the identification of compounds capable of inhibiting biofilm formation. A collection of marine sponge isolated bacteria were screened for the ability to inhibit the central pathway regulating biofilm formation, quorum sensing. A number of distinct isolates were identified that had quorum sensing inhibition activity from which, a Pseudomonas isolate was selected for further characterisation. A specific compound capable of inhibiting quorum sensing was identified using chemical analytical technologies in the supernatant of this marine isolate.

Spanish Sociology and Anti-Semitism Between passed prejudice and key to civilization

There is a significant lack of sociological research in Spain about anti-Semitism. At the same time there are alarming anti-Semitic tendencies and anti-Jewish stereotypes which are above the European average. This article aims to explain this lack of sociological research about anti-Semitism in Spain. Therefore two types of explications are offered: on the one hand side some structural problems will be shown which sociology in general had since its beginnings and which complicate the understanding of anti-Semitism. Furthermore explications regarding the specific social and historic situation in Spain and of Spanish sociology in particular will be exposed. It will be shown that for its rationalistic character and with the exception of very few authors – who are considered marginalized for practical research – sociology in general has had enormous problems in understanding anti-Semitism. The specific historic situation, Francoism, the dispute about the historic memory and the delayed institutionalisation of sociology could also explain the lack of sociological interest in the topic especially in Spain. The article shows that the study of anti-Semitism is not only relevant for struggling against this burden of society in many of its variants. Furthermore, thinking about anti-Semitism can help sociology to recognise its own epistemological problems. It can serve to criticise and improve instruments of sociological research by showing the limitations of the sociological approach and to uncover the importance of interdisciplinary research for understanding specific social phenomena. In that sense, anti-Semitism, far from being a marginal subject, can be considered a key topic in the process of civilisation and it can help us to decipher the contemporary Spanish society.

Plane wave and Coulomb asymptotics

A simple plane wave solution of the Schrodinger-Helmholtz equation is a quantum eigenfunction obeying both energy and linear momentum correspondence principles. Inclusion of the outgoing wave with scattering amplitude f asymptotic development of the plane wave, we show that there is a problem with angular momentum when we consider forward scattering at the point of closest approach and at large impact parameter given semiclassically by (l + 1/2)/k where l is the azimuthal quantum number and may be large (J. Leech et al., Phys. Rev. Lett. 88. 257901 (2002)). The problem is resolved via non- uniform, non-standard analysis involving the Heaviside step function, unifying classical, semiclassical and quantum mechanics, and the treatment is extended to the case of pure Coulomb scattering.

Examining the introduction of legislation in Ireland to tackle juvenile anti-social behaviour

In July 2006, the Irish Parliament passed legislation aimed at tackling anti-social behaviour following a perceived increase in the problem. The new provisions are based on existing law and practice in England and Wales. However, the legislation includes a framework for dealing with juveniles that differs in a number of respects from that which exists in England and Wales. This article examines how the Irish legislation proposes to treat juveniles engaged in antisocial behaviour and contrasts this with the English approach.

The relationship between BMI and the prescription of anti-obesity medication according to social factors: a population cross sectional study

Background: Obesity is a global public health problem. There are a range of treatments available with varying short and long term success rates. One option is the use of anti-obesity medication the prescription of which has increased dramatically in recent years. Despite this, little is known about the individual and GP practice factors that influence the prescription of anti-obesity medication. Methods: Multi-level logistic regression analysis was used to investigate factors associated with the prescription of anti-obesity medication in Northern Ireland using a population primary care prescribing database (~1.5 million people aged 16+ years) during 2009/10. Results: While 25.0% of people are obese, only 1.3% (2.1% of females, 0.6% of males) received anti-obesity medication. The relationship between medication rates and age differed by gender (P < 0.001) with prescriptions higher in younger females and older males. Prescribing of anti-obesity medication reflected obesity prevalence across urban/rural areas and deprivation. There was an unexplained two-fold difference, between the 25th and 75th percentile, in the GP practice prescription of anti-obesity medication. Conclusions: There is evidence of relative under-prescribing in males compared to females despite a similar prevalence of obesity. While the prevalence (and presumably the health consequences) of obesity worsens with age, younger females are more likely to be prescribed anti-obesity medication. This suggests an element of patient demand. Educational material to improve the understanding of the role of anti-obesity medication, for patients and practitioners, is recommended. But further study is needed to understand the factors responsible for the variation in prescribing between GP practices.

In Vitro and In Vivo Anti-Schistosomal Activity of the Alkylphospholipid Analog Edelfosine

Background: Schistosomiasis is a parasitic disease caused by trematodes of the genus Schistosoma. Five species of Schistosoma are known to infect humans, out of which S. haematobium is the most prevalent, causing the chronic parasitic disease schistosomiasis that still represents a major problem of public health in many regions of the world and especially in tropical areas, leading to serious manifestations and mortality in developing countries. Since the 1970s, praziquantel (PZQ) is the drug of choice for the treatment of schistosomiasis, but concerns about relying on a single drug to treat millions of people, and the potential appearance of drug resistance, make identification of alternative schistosomiasis chemotherapies a high priority. Alkylphospholipid analogs (APLs), together with their prototypic molecule edelfosine (EDLF), are a family of synthetic antineoplastic compounds that show additional pharmacological actions, including antiparasitic activities against several protozoan parasites.

Methodology/Principal Findings: We found APLs ranked edelfosine> perifosine> erucylphosphocholine> miltefosine for their in vitro schistosomicidal activity against adult S. mansoni worms. Edelfosine accumulated mainly in the worm tegument, and led to tegumental alterations, membrane permeabilization, motility impairment, blockade of male-female pairing as well as induction of apoptosis-like processes in cells in the close vicinity to the tegument. Edelfosine oral treatment also showed in vivo schistosomicidal activity and decreased significantly the egg burden in the liver, a key event in schistosomiasis.

Conclusions/Significance: Our data show that edelfosine is the most potent APL in killing S. mansoni adult worms in vitro. Edelfosine schistosomicidal activity seems to depend on its action on the tegumental structure, leading to tegumental damage, membrane permeabilization and apoptosis-like cell death. Oral administration of edelfosine diminished worm and egg burdens in S. mansoni-infected CD1 mice. Here we report that edelfosine showed promising antischistosomal properties in vitro and in vivo.