Tracking Resistance Research Articles

Experimental comparison of the lateral resistance of tracks with steel slag ballast and limestone ballast materials

Extending the use of continuous welded rails by eliminating the weak points (expansion joints) of a railway track especially in sharp curves, which has resulted in increasing the operational speed and axle load of rolling stocks, enhances the special attention to the issue of track lateral resistance. In this regard, the ballast layer interaction with sleepers plays a crucial role in providing the track lateral stability. In many railway projects supplying the appropriate ballast materials has encountered serious restrictions owing to the lack of qualified ore and also their long distance to the project’s site. With the development of steel industry, the quantity of production and accumulation of steel slag as a waste material has increased. In recent years, a great deal of attention has been paid to the use of this material as railway ballast. According to the physical and mechanical characteristics of steel slags, such as high specific gravity and the granular roughness respect to the limestone ballast, the usage of slag ballast can improve the track lateral stability. In this research, many field experiments were conducted on tracks with steel slag ballast and limestone ballast materials considering the same gradation. In this matter, several single tie push tests were carried out on both tracks with various ballast geometries. The ballast depth was considered as 30, 40, and 50 cm and the shoulder ballast width was equal to 30 and 40 cm. Moreover, the shoulder ballast height was chosen 0 and 10 cm. Consequently, the lateral resistance of both tracks was measured and compared in the same conditions. In overall, the obtained results confirmed a 27% increase in lateral resistance of track with steel slag ballast respect to that with limestone ballast.

Whole-genome sequencing to determine transmission of Neisseria gonorrhoeae: an observational study

New approaches are urgently required to address increasing rates of gonorrhoea and the emergence and global spread of antibiotic-resistant Neisseria gonorrhoeae. We used whole-genome sequencing to study transmission and track resistance in N gonorrhoeae isolates. We did whole-genome sequencing of isolates obtained from samples collected from patients attending sexual health services in Brighton, UK, between Jan 1, 2011, and March 9, 2015. We also included isolates from other UK locations, historical isolates from Brighton, and previous data from a US study. Samples from symptomatic patients and asymptomatic sexual health screening underwent nucleic acid amplification testing; positive samples and all samples from symptomatic patients were cultured for N gonorrhoeae, and resulting isolates were whole-genome sequenced. Cefixime susceptibility testing was done in selected isolates by agar incorporation, and we used sequence data to determine multi-antigen sequence types and penA genotypes. We derived a transmission nomogram to determine the plausibility of direct or indirect transmission between any two cases depending on the time between samples: estimated mutation rates, plus diversity noted within patients across anatomical sites and probable transmission pairs, were used to fit a coalescent model to determine the number of single nucleotide polymorphisms expected. 1407 (98%) of 1437 Brighton isolates between Jan 1, 2011, and March 9, 2015 were successfully sequenced. We identified 1061 infections from 907 patients. 281 (26%) of these infections were indistinguishable (ie, differed by zero single nucleotide polymorphisms) from one or more previous cases, and 786 (74%) had evidence of a sampled direct or indirect Brighton source. We observed multiple related samples across geographical locations. Of 1273 infections in Brighton (including historical data), 225 (18%) were linked to another case elsewhere in the UK, and 115 (9%) to a case in the USA. Four lineages initially identified in Brighton could be linked to 70 USA sequences, including 61 from a lineage carrying the mosaic penA XXXIV allele, which is associated with reduced cefixime susceptibility. We present a whole-genome-sequencing-based tool for genomic contact tracing of N gonorrhoeae and demonstrate local, national, and international transmission. Whole-genome sequencing can be applied across geographical boundaries to investigate gonorrhoea transmission and to track antimicrobial resistance. Oxford National Institute for Health Research Health Protection Research Unit and Biomedical Research Centre.

New Prepregs Based on Unsaturated Polyester Resins Modified with Polysiloxane Oligomers

A formulation has been developed for a glass-fibre-filled moulding compound based on a composite of unsaturated polyester resin and α,ω-bis(vinyldimethyl) polydimethylsiloxane, articles of which possess increased surface water repellency. In the course of tracking and erosion resistance tests after surface hydrophilisation, it was shown that the developed materials possess properties of self-recovery of water repellency.

Properties of Polymer Composites Used in High-Voltage Applications.

The present review article represents a comprehensive study on polymer micro/nanocomposites that are used in high-voltage applications. Particular focus is on the structure-property relationship of composite materials used in power engineering, by exploiting fundamental theory as well as numerical/analytical models and the influence of material design on electrical, mechanical and thermal properties. In addition to describing the scientific development of micro/nanocomposites electrical features desired in power engineering, the study is mainly focused on the electrical properties of insulating materials, particularly cross-linked polyethylene (XLPE) and epoxy resins, unfilled and filled with different types of filler. Polymer micro/nanocomposites based on XLPE and epoxy resins are usually used as insulating systems for high-voltage applications, such as: cables, generators, motors, cast resin dry-type transformers, etc. Furthermore, this paper includes ample discussions regarding the advantages and disadvantages resulting in the electrical, mechanical and thermal properties by the addition of micro- and nanofillers into the base polymer. The study goals are to determine the impact of filler size, type and distribution of the particles into the polymer matrix on the electrical, mechanical and thermal properties of the polymer micro/nanocomposites compared to the neat polymer and traditionally materials used as insulation systems in high-voltage engineering. Properties such as electrical conductivity, relative permittivity, dielectric losses, partial discharges, erosion resistance, space charge behavior, electric breakdown, tracking and electrical tree resistance, thermal conductivity, tensile strength and modulus, elongation at break of micro- and nanocomposites based on epoxy resin and XLPE are analyzed. Finally, it was concluded that the use of polymer micro/nanocomposites in electrical engineering is very promising and further research work must be accomplished in order to diversify the polymer composites matrices and to improve their properties.

Functional behaviors of electric field grading composite materials

Non-linear resistive field grading materials (FGM) are used in different high voltage applications e.g. cable terminations, joints and rotating machines, where the electric stress is critical. It is already established that the use of FGM is an improved stress grading technique compared to conventional geometric methods. There is a constant endeavor within the electric power industries to extend these concepts to other power equipment. In order to achieve a wide spread use of FGM, they need to satisfy several functional requirements e.g. fire safety, tracking resistance, hydrophobicity, high thermal conductivity, besides certain dielectric properties e.g. field dependent conductivity, permittivity and low dielectric losses. In the present study ZnO filled silicon rubber (SiR) composite with different functional fillers, in total six different material compositions, are evaluated with respect to several important functional behaviors. Further, stress grading behavior of these six materials are demonstrated by finite element simulations on a generic electrode geometry and by performing inclined plane tracking test. Suitability of these material compositions to industrial applications are discussed.

Track–Bridge Interaction Analysis Using Interface Elements Adaptive to Various Loading Cases

In this paper, a numerical model using interface elements is proposed for the sequential analysis of nonlinear track–bridge interaction by taking the loading history into consideration. Longitudinal resistance tests were conducted on track fastening systems to determine changes in track resistance that occur at the instant of application or release of a vertical load. On the basis of the test results, longitudinal track stiffness laws for a nonballasted track were established for different loading cases including constant vertical load, sudden application of vertical load, and sudden release of vertical load. In addition, an interface element adaptive to various loading cases that can be incorporated into a conventional FEM was formulated for modeling the track resistance. Furthermore, a numerical algorithm for a practical solution of the nonlinear system equation was developed. The validity and applicability of the proposed analysis method were verified by conducting extensive parameter studies on a simply supported bridge and a multispan bridge.

The impact of Hisingerite on asphalt shear resistance

Two Marshall-designed asphalt mixtures were developed with common coarse aggregate, added filler (1% hydrated lime) and bituminous binder (5.8% acid-modified bitumen). The target aggregate grading and overall volumetrics were not significantly different. Different fine aggregate (dust sources) were used in each asphalt mixture. Dust A contained predominantly Nontronite clay minerals while 82% of the Dust B clay minerals were identified as Hisingerite. Hisingerite is a rarely encountered and poorly studied clay mineral. Specialist geotechnical interpretation of its unique properties indicated potentially adverse impact on mastic stability and asphalt shear response. This research assessed the impact of Hisingerite clay on otherwise identical asphalt mastic, as an indicator of the impact of Hisingerite-rich dust sources on asphalt performance. Six M1000 (acid-modified) bitumen samples were each used to manufacture two mastic samples, one containing each fine aggregate. The same hydrated lime was added, and all mastic samples were manufactured with constant proportions of bitumen, added filler and fine aggregate, representative of the asphalt mixture designs. Wheel tracking, resilient modulus, tensile strength and moisture resistance testing did not indicate any detrimental effects from Hisingerite-rich Dust B nor did mastic complex modulus master curves. Multiple stress creep recovery testing found the Dust B mastic to deform less than Dust A mastic under cyclic shear. This was concluded to likely reflect the lower density and higher absorption of the Dust B fine aggregate. Despite the concerning physical properties, it was concluded that the incorporation of Hisingerite-rich fine aggregate presented no risk to asphalt performance. It follows that there is no basis for additional routine testing of potential dust sources to identify Hisingerite content. This research also highlighted the importance of controlling mastic composition during testing, with further testing at a constant ‘effective’ binder volume required. Maintaining the filler dosage constant relative to the mass (or volume) of the dust (or the bitumen) must also be considered.

Tracking Down Response and Resistance to TRK Inhibitors.

Two recent studies validate the LMNA-NTRK1 fusion as an oncogenic driver and therapeutic target of TRK inhibitors. The LMNA-NTRK1 fusion occurs at low frequency across multiple tumor types. The studies highlight the increasing need to develop molecular biomarker-based clinical trials across cancer subtypes.

Comparison of Voltage-time to Surface Failure of Various Insulation Material for Space Aerial Cables

This paper aims to represents the investigation of surface tracking resistance of various types of cable insulations. Five kinds of cable material i.e. non carbon filled crosslink polyethylene (XLPE), carbon filled XLPE, low density polyethylene (LDPE), medium density polyethylene (MDPE), and high density polyethylene (HDPE) were examined. The test specimen has a dimension of 10 mm in width, 50.8 mm in length and 1.52 mm in thickness. The test samples were classified into two groups for investigation. The former group was the new test samples, whereas the latter test samples were stressed by thermal ageing with 120oC for 168 hours. Then both specimens were examined. One side of the specimen was contacted with high voltage electrode terminal made of 1 mm diameter Nichrome wire. Another side of the test specimen was dipped into 0.1 percent solution of ammonium chloride as grounded electrode. The spacing between electrodes at dry area was determined for 25.4 mm. After completion of the test set up, AC high voltage was applied to the test specimen. The dip rate of the specimen into the solution was set up as 4 times per minute. The test voltage level was in the range of 1-3.5 kV. The experiment was performed in accordance with ICEA S-66-524 (Method B). The test voltage was applied to the test specimen until the insulation failure could be observed. Then, the insulation failure voltage and failure time were recorded. The test results illustrated that both unaged and aged HDPE and non carbon filled XLPE provided the higher surface tracking resistance than carbon filled XLPE, LDPE and MDPE respectively. Besides, the thermal stress aging had not much effect on the surface tracking resistance characteristic of tested material. It can be summarized that the material structure much more influenced the surface tracking characteristic of the cable material.

궤도의 성능향상을 위한 탄성구성요소로 통합된 상부구조 설계

Track elastic components can be technically and economically efficient when integrated well into track superstructure of a railway network. In such cases, the elastic rail pad is larger than a 800m radius curve provides smooth rail branching and allows for high-speed operation (). High track resistance causes the tamping intervals to stand out because the constantly increasing share of the sleeper pad further extends the increase of the tamping interval and the long grinding period; the engineering and construction of the small curve radius track provides some measures for reducing the solid sounds. Installation of elastic mats under the ballast can have a good effect, particularly in the context of protection against dust during construction or extensive renovation measures when laying new lines. However, such a process requires special attention and proper installation.

An Elliptic Curve Cryptography-Based RFID Authentication Securing E-Health System

Mobile healthcare (M-health) systems can monitor the patients’ conditions remotely and provide the patients and doctors with access to electronic medical records, and Radio Frequency Identification (RFID) technology plays an important role in M-health services. It is important to securely access RFID data in M-health systems: here, authentication, privacy, anonymity, and tracking resistance are desirable security properties. In 2014, He et al. proposed an elliptic curve cryptography- (ECC-) based RFID authentication protocol which is quite attractive to M-health applications, owing to its claimed performance of security, scalability, and efficiency. Unfortunately, we find their scheme fails to achieve the privacy protection if an adversary launches active tracking attacks. In this paper, we demonstrate our active attack on He et al.'s scheme and propose a new scheme to improve the security. Performance evaluation shows the improved scheme could meet the challenges of M-health applications.

Design and Analysis on Symmetric MEMS Inductor

This paper presents the design and analysis of new proposed topology micro-electro-mechanical system (MEMS) inductor. This new symmetric MEMS inductor is designed to reduce the total length of the conductor strip and hence reduce the resistance of the metal tracks. This results significant increases in the quality (Q) factor of the inductor. In this paper, the MEMS inductor is designed using CoventorWare®, which is powerful software for MEMS computer aided design (CAD), modeling and simulation. Results indicate that new symmetric inductor topology has thehighest Q-factor and it hasbeenimproved bytwo times compared to circular inductor. The analysis revealed that area of the symmetric inductor has reduced by37.5% compared to the circular inductor. Result has proved that the reduction of length of the conductor strip has reduced the resistance of the metal tracks and results in a high Q-factor inductor.

Allelic Variation of Cytochrome P450s Drives Resistance to Bednet Insecticides in a Major Malaria Vector.

Scale up of Long Lasting Insecticide Nets (LLINs) has massively contributed to reduce malaria mortality across Africa. However, resistance to pyrethroid insecticides in malaria vectors threatens its continued effectiveness. Deciphering the detailed molecular basis of such resistance and designing diagnostic tools is critical to implement suitable resistance management strategies. Here, we demonstrated that allelic variation in two cytochrome P450 genes is the most important driver of pyrethroid resistance in the major African malaria vector Anopheles funestus and detected key mutations controlling this resistance. An Africa-wide polymorphism analysis of the duplicated genes CYP6P9a and CYP6P9b revealed that both genes are directionally selected with alleles segregating according to resistance phenotypes. Modelling and docking simulations predicted that resistant alleles were better metabolizers of pyrethroids than susceptible alleles. Metabolism assays performed with recombinant enzymes of various alleles confirmed that alleles from resistant mosquitoes had significantly higher activities toward pyrethroids. Additionally, transgenic expression in Drosophila showed that flies expressing resistant alleles of both genes were significantly more resistant to pyrethroids compared with those expressing the susceptible alleles, indicating that allelic variation is the key resistance mechanism. Furthermore, site-directed mutagenesis and functional analyses demonstrated that three amino acid changes (Val109Ile, Asp335Glu and Asn384Ser) from the resistant allele of CYP6P9b were key pyrethroid resistance mutations inducing high metabolic efficiency. The detection of these first DNA markers of metabolic resistance to pyrethroids allows the design of DNA-based diagnostic tools to detect and track resistance associated with bednets scale up, which will improve the design of evidence-based resistance management strategies.

The Behaviour of the Embedded Rail in Interaction with Bridges

Since the introduction of the direct fastening system, Embedded Rail System (ERS) is probably one of the most spectacular and innovative developments in railway engineering. The development has become more rapid, especially in the last decade due to competitive advantages in comparison toother systems with respect to higher speed, cost effectiveness, environmental-material sustainability and others. But still there is a lack of specific interaction model, especially when it comes to bridges equipped with ERS system. Previous studies on ERS by Estzer Ludvigh2 found out some important coefficients (vertical and longitudinal bedding coefficient) and compared the longitudinal resistance of ERS with flexible fastening systems. Other studies on ERS do not specifically deal with the evaluation of longitudinal resistance of such a system. With a view to establish the typical behaviour pattern of ERS, this paper is dedicated to find out the interaction of a specific Embedded Rail System with bridges. A small scale test was conducted on a sample of ERS in the laboratory under different combinations of vertical and longitudinal track loads and subsequently a Finite Element Model (FEM) was developed to simulate the test. The paper presents the FEA result validation with test results, the interaction pattern, longitudinal resistance of ERS track for both loaded and unloaded conditions, design load distribution for such systems and some specific influences of ERS on simply supported bridge systems.

Using the inclined-plane test to evaluate the resistance of outdoor polymer insulating materials to electrical tracking and erosion

Evaluating the electrical tracking and erosion resistance of polymeric housing materials is an essential task performed in the development of outdoor insulators. “Tracking” means the formation of a surface carbonaceous path, and “erosion” means weight loss of the housing material. An absolute measurement of the tracking and erosion resistance is not possible; only relative ranking of composites can be achieved using the standard tracking and erosion tests. During the early use of organic insulating materials, failure due to tracking was a major concern, and therefore standard screening methods were proposed to evaluate the tracking rather than the erosion resistance. Erosion has become more important following the development of trackingresistant composites containing high levels of inorganic fillers.

A risk assessment method for ballast flight; managing the rolling stock/infrastructure interaction

The evaluation of the level of risk resulting from the phenomenon of ballast flight is currently receiving considerable attention, due to its direct impact on the safety and reliability of commercial railway operations. Of particular interest are the effects of this phenomenon on both railway infrastructure and rolling stock. It is difficult to analyse the ballast flight phenomenon, due to its dependence on a large number of variable parameters. Investigations carried out at SNCF have led to the proposal of a global approach, called the stress–strength interference analysis method, which can be applied by considering a relevant indicator to evaluate the risk due to flying ballast. This paper presents the work on the application of the proposed analysis approach to the ballast flight phenomenon performed within the FP7 EU AeroTRAIN project. The approach considers the influence of the passage of dedicated rolling stock and the resistance of the track to the displacement of ballast. It leads to the proposal of a methodology to evaluate the risk of ballast flight in high-speed rail operations; this allows the evaluation of the degradation rate of railway infrastructure and rolling stock due to this phenomenon to be performed.

Non-Linear Insulator Performance of Wind Turbine Blade Surface against Lightning Strike

This research work investigates the surface degradation of blade specimen which is made from epoxy resin mixed with non-linear fillers of Zinc oxide, Aluminium oxide and Sodium silicate in different ratio percentage. Test on surface trackability of each specimen according to IEC 60587 standard. Then, choose the best specimen which has achieved a high tracking resistance to test against lightning impulse voltage according to IEC 60243-3 at ± 60 kVpeak. A comparison has been made with the pure epoxy resin specimen as a controlled sample. The results showed that, the epoxy resin specimen with the ratio of 40% by weight of Aluminium oxide filler slow down the tracking process better than other specimen type. And from the result of lightning impulse withstand voltage test, it is found that all of the specimen were not affected.

English

The obligate root parasitic weed Striga gesnerioides poses a severe constraint to cowpea productivity in the dry savannahs of West and Central Africa, where cowpea is a major crop. At least seven races of S. gesnerioides have been identified within the cowpea-growing regions of West and Central Africa, based on host differential response and genetic diversity analysis. Molecular markers linked to resistance to different races of S. gesneriodes have been identified. It was desirable to demonstrate the applicability and efficiency of such markers for use in marker-assisted selection (MAS) to fast-track the development of cowpea with resistance to S. gesnerioides. The objective of the study was to determine the suitability of two molecular markers in tracking resistance in cowpea to S. gesnerioides race SG3, the predominant race found in Nigeria. F2 mapping populations and recombinant inbred lines (RILs) derived from the cross involving IT97K-499-35 and a susceptible local landrace (Borno Brown), and another resistant parent B301 with the same susceptible land race (Borno Brown) were assayed using two linked markers. Genetic analysis showed that resistance to S. gesnerioides in cowpea is inherited as a single dominant gene. Two SCAR markers, 61RM2 and C42-2B were validated in the same F2 populations and subsequent recombinant inbred lines (RILs). The two markers were able to discriminate between resistance and susceptibility and the genotypic score was quite similar to the phenotypic score with the markers score showing greater efficiency in selection than phenotypic score. The 61RM2 had two bands in resistant cultivars and amplified a ~450 bp fragment with marker efficiency of 98% while C42-2B amplified a single ~250 bp fragment with marker efficiency of 96% in resistant cultivars and absent in susceptible cultivars. The genetic distance between 61RM2 and phenotypic score was 3.5 cM while that of C42-2B and phenotypic score was 8.5 cM. The two marker data set were significantly correlated with the phenotypic data (r=0.95). Based on the tight linkage with the resistant locus, 61RM2 was found to be a utility marker to initiate MAS in cowpea breeding for resistance to S. gesnerioides.   Key words: Cowpea, Striga, molecular marker, genetic distance, race-specific, obligate parasitic weed, Vigna unguiculata. &nbsp

Resistance to receptor tyrosine kinase inhibition in cancer: molecular mechanisms and therapeutic strategies.

Drug resistance is a major factor that limits the efficacy of targeted cancer therapies. In this review, we discuss the main known mechanisms of resistance to receptor tyrosine kinase inhibitors, which are the most prevalent class of targeted therapeutic agent in current clinical use. Here we focus on bypass track resistance, which involves the activation of alternate signaling molecules by tumor cells to bypass inhibition and maintain signaling output, and consider the problems of signaling pathway redundancy and how the activation of different receptor tyrosine kinases translates into intracellular signal transduction in different cancer types. This information is presented in the context of research strategies for the discovery of new targets for pharmacological intervention, with the goal of overcoming resistance in order to improve patient outcomes.

Tracking resistance of epoxy/Al<sub>2</sub>O<sub>3</sub> nanocomposites under DC voltage

Based on the viewpoint that the properties of polymer could be changed by nano particles, epoxy/Al2O3 nanocomposites were prepared to study the effects of nano particles on tracking failure. Nano-Al2O3 particles were mixed into neat epoxy with filler content of 1, 3, 5 and 7 wt%. Tracking experiments were carried out by applying positive dc voltage. The effects of the filler content on tracking resistance were studied by recording the tracking phenomena and discharge currents during the tracking process. Obtained results showed that when the filler content increased from 0 to 5 wt%, the duration of the whole tracking process increased, the weight loss of nanocomposites and the area of tracking pattern decreased. The opposite tendency was observed when the content increased from 5 to 7 wt%. The discharge currents were studied using the recurrence plot technique to investigate the nonlinear characteristics of discharge currents and reflect the effects of nano particles on discharge. The fractal dimension method was used to study the structures of scintillation discharge distribution and tracking pattern to analyze the effects of nano particles on the occurrence of tracking pattern. The results showed that the nano-Al2O3 particles had very significant effects on the tracking resistance of epoxy. The best restriction effects were obtained with the filler content of 5 wt%.