Experimental analysis on calibration of instrument broadening in a lidar system with Fabry–Perot etalon

A Brillouin lidar system based on a Fabry–Perot (F-P) etalon and intensified charge coupled device (ICCD) is widely used in measuring ocean physical properties. In previous signal detecting methods, the resolution of the obtained Brillouin spectrum is the major limitation on measurement accuracy of the Brillouin spectrum. The effect due to the instrument of the F-P etalon is relatively minor and typically neglected. However, because methods for obtaining a high resolution spectrum have greatly improved the spectral resolution, the instrument broadening has become the major error source and should be taken into consideration in the measurement. Instrument broadening is a common topic and has been widely researched. Unfortunately, for applications involving a high resolution spectrum, no detailed study has analyzed the performance of the methods for calibrating the broadening with high resolution experimental data. In this paper, the capability and the time costs of methods for reducing the broadening effect are evaluated for a high resolution spectrum obtained from underwater experiments. We also discuss in detail the implementation of the methods. Experimental results show that the three methods considered can effectively calibrate the broadening effect and improve the measurement accuracy from tens of MHz to MHz magnitude. Considering the similar performance of the methods, one method that is sufficient for online measurement is recommended as the optimal method.     

Safety analysis in design—Evaluation of a case study

Safety analysis was applied in the design of a section at a paper mill. The case study involved analysis of layout, transport system, machines, and a number of different activities. The purpose of the analysis was to find measures to decrease occupational accidents. Three years after the installation was finished the occurrence of accidents was investigated. There was a 56% decrease in the number of accidents; the number of working days lost due to accidents was diminished by 75% as compared to 4 years preceding. The results of the safety analysis were also evaluated with respect to the accidents which had occurred. The methods for safety analysis seem to have been efficient in identifying hazards. The general conclusion of the study is that safety analysis can be an effective tool to decrease occupational accident risks.     

The analysis of elastic liner in a cylindrical tunnel subjected to sh‐waves

Abstract

In this paper, we investigate the dynamic stresses of an elastic liner around a cylindrical tunnel subjected to an incident plane SH‐wave in an infinitely extended elastic medium. The investigation is based on the anti‐plane strain approximation of the dynamic theory of elasticity. The solutions are obtained by applying the method of wave functions expansion. Numerical results of dynamic stress concentrations at the outer and inner boundaries of the liner for various parameters are discussed in detail.     

Failure of planetary pinions in earth moving equipment—a failure analysis approach

A series of failures of planetary pinions occurred in the final drive epicyclic gearbox of large trucks used in underground mining. A metallurgical analysis indicated that failure had occurred by internal rupture of the gear. This was attributed to poor heat treatment procedures used in case hardening the gear. This had induced high residual stresses just below the case/core interface, leading to the internal rupture of the gear.     

The application of the entropy measure to the analysis of part commonality in a product line†

Given the objective of determining the degree of part commonality in a product line, this study discusses several methods of analysis which are possible. The use of the entropy measure, H= ? σpi log pi, is investigated as a plausible alternative to current procedure. The methodology will incorporate a simulation of several types of distributions of part usage which might occur in a typical application. An analysis of the results will compare the entropy approach with existing practice.     

An Attempt at Bringing to Light a “Phase Inversion” in a Binary Mixture of Two Dimensional Rounded Particles

Abstract

It has been demonstrated previously in our Laboratory that the disintegrant concentration corresponding to an interparticular network between drug or diluent particles in tablets may be calculated.

When the disintegrant concentration increases little by little, for a critical concentration, a sudden modification of the physical properties of the powder mixture and of the resulting tablets can be observed.

A new structure is set up in the tablet: in a way, a “phase inversion” is produced.

This experimental critical concentration is the same as the calculated critical concentration for more or less rounded particles.

An investigation into the physical properties of binary powder mixtures and of resulting tablets is carried out when increasing, little by little, the quantity of disintegrant particles: Starches and their derivatives, cross linked PVP, are more particularly studied.

The authors study:

• – The flowing properties of powder mixtures

• – The compressibility (Hardness/Compression forces, transmission forces through the powder mixture during compression, compression cycles…)

• – The physical properties of tablets (hardness, structure hydrophilicity, disintegration time and drug dissolution).

Several formulations were studied. The results point out the setting up of the continuous network of the small particles between the larger particles for the calculated critical concentration. The same theory may be applied to the hydrophilization of powders in hard gelatin capsules and to all the more o r less rounded two dimensional particles in a mixture.     

Application of a dynamic numerical solution to high speed fracture experiments—I. analysis of experimental geometries

The application of a dynamic, generation mode, finite element program to the analysis of experimental geometries is reported. Particular attention is given to the DCB specimen, which is widely used in high speed fracture studies despite strong inertia effects, which are described. Finite strip and infinite plate results are also considered. Here, idealised cases are discussed, while in Part II the application of the analysis to experimental measurements, to derive propagating crack fracture resistance data, is reported.     

Public–private contribution to biopharmaceutical discoveries: a bibliometric analysis of biomedical research in UK

Scientometrics - Basic research creates new knowledge that fuels technological advances. However, budgetary concerns and escalating R&D prices are challenging organizations to show returns...     

Use of time history speckle pattern and pulsed photoacoustic techniques to detect the self-accommodating transformation in a Cu–Al–Ni shape memory alloy

Continuous and pulsed electromagnetic radiation was used to detect the self-accommodation mechanism on a polycrystalline Cu–13.83 wt.%Al–2.34 wt.%Ni shape memory alloy. Rectangular samples of this alloy were mechanically polished to observe the austenite and martensite phases. The samples were cooled in liquid nitrogen prior to the experiments to obtain the martensite phase. Using a dynamic speckle technique with a continuous wave laser we obtained the time history of the speckle pattern image and monitored the surface changes caused by the self-accommodation mechanism during the inverse (martensitic to austenitic) transformation. Using a photoacoustic technique based on a pulsed laser source it was also possible to detect the self-accommodation phenomena in a bulk sample. For comparison purposes, we used differential scanning calorimetry (DSC) to detect the critical temperatures of transformation and use these as reference to evaluate the performance of the optical and photoacoustical techniques. In all cases, the same range of temperature was obtained during the inverse transformation. From these results, we conclude that time history speckle pattern (THSP) and pulsed photoacoustic are complementary techniques; they are non-destructive and useful to detect surface and bulk martensitic transformation induced by a temperature change.     

Stress concentration due to a rigid ribbon in the presence of a crack—I. SH case

The stress intensity factors in the regions close to rigid ribbon like inclusions caused by the presence of a crack are studied. Here we treat the SH-wave motion taking the crack to be semiinfinite and the ribbon finite. Both loading over the crack face by prescribed tractions as well as excitation due to a plane wave incidence are considered. Several numerical results are computed.     

Biomimetic structure design — a possible approach to change the brittleness of ceramics in nature

Based on the analysis on structure of natural biomaterials, two kinds of ceramic composites with high toughness have been designed and prepared: one is fibrous monolithic Si₃N₄/BN composite imitating bamboos or trees in structure, the other is laminated Si₃N₄/BN composite imitating nacre in structure. Plastic forming methods, including extrusion and roll compaction, respectively, followed by hot-pressed sintering are used to prepare these two materials with particular structures. Both of the two composites have high values of fracture toughness and work of fracture: fracture toughness are 24 MPa m^1/2 and 28 MPa m^1/2, respectively, for fibrous monolithic and laminated Si₃N₄/BN composites, and works of fracture are both more than 4000 J/m². The load-displacement curves reveal that these two materials with biomimetic structure exhibit non-brittle feature when applied load to fracture. Through analysis on fractographs of the materials, it is revealed that high toughness comes from the synergistic toughening among multi-level toughening mechanisms in different scales: weak interfaces, whiskers and elongated grains toughening in ceramic matrix cells.     

Bibliometric analysis to identify an emerging research area: Public Relations Intelligence—a challenge to strengthen technological observatories in the network society

Scientometrics - Nowadays within the global economy, organizations of all kinds require strategic information to ensure that their decision making is competitive in uncertain complex environments....     

Anomalies of Physical Properties inα-Bi2O3 — a Phase Transition Governed by the Electronic Mechanism?

A number of physical properties of -Bi₂O₃ was studied: the thermal expansion, thermally stimulated conductivity, electrical resistivity, and dielectric permeability. X-ray diffraction, DTA, and differential scanning calorimetry measurements were also carried out. Several anomalies were observed: a small maximum and drastic rise of the single crystal dielectric permeability, a sharp drop of the electric resistivity, a jump and change in sign of the thermally stimulated current, and an exothermal maximum in differential heat capacity. At the same time, the monoclinic lattice symmetry of -Bi₂O₃ was retained over the temperature range where these anomalies were found.     

Response to the letter ‘Field classification of publications in Dimensions: a first case study testing its reliability and validity’

Scientometrics - With Dimensions, Digital Science provides the research community a new approach on research related information, bringing formerly siloed content types such as grants, patents,...     

Is there a golden age in publication activity?—an analysis of age-related scholarly performance across all scientific disciplines

Scientometrics - We examined whether the publication characteristics of various scientific disciplines exhibit age-related trends. Our analysis was based on two large data sets comprising all major...     

Same data—different results? Towards a comparative approach to the identification of thematic structures in science

Science studies are persistently challenged by the elusive structures of their subject matter, be it scientific knowledge or the various collectivities of researchers engaged with its production. Bibliometrics has responded by developing a strong and growing structural bibliometrics, which is concerned with delineating fields and identifying thematic structures. In the course of these developments, a concern emerged and is steadily growing. Do the sets of publications, authors or institutions we identify and visualise with our methods indeed represent thematic structures? To what extent are results of topic identification exercises determined by properties of knowledge structures, and to what extent are they determined by the approaches we use? Do we produce more than artefacts? These questions triggered the collective process of comparative topic identification reported in this special issue. The introduction traces the history of bibliometric approaches to topic identification, identifies the major challenges involved in these exercises, and introduces the contributions to the special issue.     

Investigation into the changes in bending stiffness of a textile reinforced composite due to in-plane fabric shear: Part 2 – Numerical analysis

Numerical investigations were pursued in an effort to understand the relationship between changes in the stiffness of plain-weave fabric-reinforced plates and the degree of in-plane shear within the fabric reinforcement. These numerical studies were motivated by an experimental study where the measurable geometric changes discerned among plates with different levels of in-plane shear were (1) the reorientation of the fibers within the plane of the plate, (2) an increase in thickness with increasing in-plane shear, and (3) the change in width of the fiber tows as function of in-plane shear. Finite element models were used to investigate the individual contributions of these geometric changes on the bending stiffness of the plates. For the material system considered in this study, the reorientation of the fibers and the change in plate thickness as a function of the state of shear were concluded to be the dominant factors affecting the bending stiffness of the plates. The change in cross-section orientation about the tow axis was determined to be insignificant.