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Journal of Instrumentation 17(05), P05022 (2022). doi:10.1088/1748-0221/17/05/P05022, The Compact Muon Solenoid collaboration is designing a new high-granularity endcap calorimeter, HGCAL, to be installed later this decade. As part of this development work, a prototype system was built, with an electromagnetic section consisting of 14 double-sided structures, providing 28 sampling layers. Each sampling layer has an hexagonal module, where a multipad large-area silicon sensor is glued between an electronics circuit board and a metal baseplate. The sensor pads of approximately 1.1 cm$^{2}$ are wire-bonded to the circuit board and are readout by custom integrated circuits. The prototype was extensively tested with beams at CERN's Super Proton Synchrotron in 2018. Based on the data collected with beams of positrons, with energies ranging from 20 to 300 GeV, measurements of the energy resolution and linearity, the position and angular resolutions, and the shower shapes are presented and compared to a detailed Geant4 simulation., Published by Inst. of Physics, London

This work was aimed in the relationships investigation among the microstructure, the tensile properties and the thermo-mechanical processing of a novel Ti-25Zr-1B (wt%) alloy. The alloy was evaluated under different conditions (as-cast, hot-rolled and hot-rolled-annealed). The XRD diagrams demonstrated that all specimens were completely consisted of the α and TiB phases. The results of EDS indicated that the TiB phase dissolved a certain amount of Zr, which was in agreement with the existence of TiB peaks shifting towards lower diffraction angles. The as-cast Ti-25Zr-1B alloy microstructure and the size, the morphology, the orientation, and the distribution of the TiB particles could be significantly altered by the hot-rolling process. The hot-rolling process provided an ultimate strength increase of at least 7 pct and the elongation-to-failure increase of 135 pct relatively to the as-cast sample. In addition, the annealing heat treatment could effectively modify the mechanical properties of the hot-rolled sample. The strength decreased and the elongation-to-failure increased as the annealing temperature increased, while the temperature was below 800 °C. In contrast, as the annealing temperature increased to 900 °C, the alloy demonstrated appreciably lower elongation-to-failure and higher strength compared to the annealed form at 800 °C. The mechanical properties variation of the Ti-25Zr-1B alloy series was ascribed to the microstructure evolution of the matrix alloy as well as to the morphology and volume fraction changes of the TiB particles.

Journal of Instrumentation 16(04), T04001 (2021). doi:10.1088/1748-0221/16/04/T04001, The CMS experiment at the CERN LHC will be upgraded to accommodate the 5-fold increase in the instantaneous luminosity expected at the High-Luminosity LHC (HL-LHC) [1]. Concomitant with this increase will be an increase in the number of interactions in each bunch crossing and a significant increase in the total ionising dose and fluence. One part of this upgrade is the replacement of the current endcap calorimeters with a high granularity sampling calorimeter equipped with silicon sensors, designed to manage the high collision rates [2]. As part of the development of this calorimeter, a series of beam tests have been conducted with different sampling configurations using prototype segmented silicon detectors. In the most recent of these tests, conducted in late 2018 at the CERN SPS, the performance of a prototype calorimeter equipped with ���12,000 channels of silicon sensors was studied with beams of high-energy electrons, pions and muons. This paper describes the custom-built scalable data acquisition system that was built with readily available FPGA mezzanines and low-cost Raspberry Pi computers., Published by Inst. of Physics, London

Journal of Instrumentation 16(04), T04002 (2021). doi:10.1088/1748-0221/16/04/T04002, As part of its HL-LHC upgrade program, the CMS collaboration is developing a High Granularity Calorimeter (CE) to replace the existing endcap calorimeters. The CE is a sampling calorimeter with unprecedented transverse and longitudinal readout for both electromagnetic (CE-E) and hadronic (CE-H) compartments. The calorimeter will be built with ���30,000 hexagonal silicon modules. Prototype modules have been constructed with 6-inch hexagonal silicon sensors with cell areas of 1.1 cm2, and the SKIROC2-CMS readout ASIC. Beam tests of different sampling configurations were conducted with the prototype modules at DESY and CERN in 2017 and 2018. This paper describes the construction and commissioning of the CE calorimeter prototype, the silicon modules used in the construction, their basic performance, and the methods used for their calibration., Published by Inst. of Physics, London

To achieve a better balance of strength and ductility for Ti-20Zr-6.5Al-4V alloy, the fully equiaxed microstructure was obtained by post-deformation annealing process following water quench. The experimental results on microstructure evolution during the applied heat treatment routes are discussed with respect to the mechanical properties.

With the aim to develop new Zr-based alloys with excellent mechanical properties, a novel Zr-0.8B (wt%) alloy was manufactured through the following steps: casting, forging, hot-rolling and annealing treatment. The microstructure and mechanical properties of the hot-rolled and annealed Zr-0.8B alloys were investigated. The microstructure of all specimens was comprised by α and ZrB2 phases. The coarse α laths and ZrB2 whiskers were significantly refined by hot rolling. Also, a high volume of dislocations and many subgrains were formed during the hot-rolling process. A high degree of recrystallization of α phase was obtained during the annealing treatment, due to the substantially stored energy in the Zr matrix and the presence of a significant amount of subgrains. The tensile strength of the annealed Zr-0.8B alloys was decreased with the increase of annealing temperature, until 800 °C, and then increased as the heat treatment temperature was further increased to 900 °C. Many factors, such as the volume fraction of ZrB2 whiskers, grain size, dislocation density, the amount of subgrains and solution strengthening, have a significant effect on the strength. However, the elongation-to-failure showed a reverse tendency compared to the tensile strength. The reasons caused fracture of the annealed Zr-0.8B alloys are primarily attributed to dislocation pile-ups and the presence of microvoids.

We report the electronic, magnetic, and optical properties of Fe–Mn co-doped SrTiO3 using density functional theory within generalized gradient approximation. The co-doping system shows a ferrimagnetic behavior. The magnetic moments of Fe and Mn atoms are reduced by the hybridization between the O atoms and metal atoms. A half-metallic characteristic is shown in the doped system. In order to investigate the influence of the co-doping on the optical properties of SrTiO3, the extinction coefficient k(ω) and refractive index n(ω) are calculated.

The effects of indium on the microstructure, transformation temperature, mechanical properties, and shape memory effect of (Ti83Ta17)85−xZr15Inx alloys were investigated. The results showed that (Ti83Ta17)85−xZr15Inx (x = 1, 3, 5)(at%) alloys were all composed of orthorhombic α"-martensitic phase. The reverse martensitic transformation starting temperature (As) was 346 °C for x = 1 and increased with increasing indium content. The Young's modulus firstly decrease then increase with the addition of Indium. When the Indium content is 1 at%, the lowest strength and the largest elongation 25.8% can be obtained. The minor addition of indium can make up for the deficiency of low plasticity and retained a relatively large shape memory recovery strain. A prefect recovery strain of 4% were obtained in all (Ti83Ta17)85−xZr15Inx alloys.

The alloying effect of Zr on β (body-centred cubic)-phase stability was investigated in α (hexagonal close packed)-type Ti–Al alloys. According to calculations and experiments, adding Zr significantly modified the β-phase stability, because Zr was identified as a β-stabilising element in these Ti–Zr–Al alloys under the solution treatment. However, the water-quenched β-phase did not continue to be preserved after aging. In addition, stress-induced α″ (orthorhombic)-phase martensite transformation would occur during deformation.

To obtain excellent mechanical properties and globular microstructure in TiZr based alloys, the variation of microstructure during hot rolling at a temperature range from α region to β region has been investigated in a TiZrAl alloy for further understanding and control of processing–structure–property relationships. Experimental results showed that when hot rolling at α region, increasing rolling temperature could enhance the progress of dynamic globularization and refine the grain structure. However, coarse grain with slender α lath appeared when rolling temperature was above the α → β transus temperature. The mechanical properties of studied alloy were also investigated with the change in rolling temperature. Outstanding mechanical properties ( σ b =1564 MPa and e =10%) were obtained when rolling at 800 °C, which was found to be the optimal rolling temperature for this alloy. The high strength and good ductility of the studied alloy make it a good candidate for a wide range of applications.

The microstructure, mechanical property behavior, and fracture characteristics of Zr–χB alloys (χ=0, 0.05, 0.3, 0.8 wt%) obtained by casting and hot-rolling were investigated. Microstructural observation indicated that the dendritic equiaxed prior-β grain morphology was slightly elongated after hot-rolling treatment. The widths of the α lath of all the hot-rolled Zr–χB alloys were similar, and the length of the α lath decreased with increasing boron concentration. Tensile test results showed that the improved strength of the Zr–χB alloys can be primarily attributed to grain refinement. Strengthening the Zr–χB alloys could also be achieved by a shear-lag model mechanism because of the high strength and modulus of the ZrB2 whiskers. The refinement of the α lath and the presence of the ZrB2 whiskers were responsible for the reduced elongation-to-failure. Fractography indicated that fracture behavior strongly depends on the orientation of the ZrB2 whiskers. The effect of this orientation on the fracture mechanisms of the ZrB2 whiskers and the Zr–χB alloys was also discussed.

Hypothalamic gonadotropin-releasing hormone (GnRH) neurons are required for fertility in all mammalian species studied to date. GnRH neuron cell bodies reside in the basal forebrain, and most extend long neurites in the caudal direction to terminate at the median eminence (ME), the site of hormone secretion. Using in vitro neurite growth assays, histological methods, and genetic deletion strategies in mice we have analysed the role of the morphogen and neurite growth and guidance molecule, Sonic hedgehog (Shh), in the growth of GnRH neurites to their target. Immunohistochemistry revealed that Shh was present in the basal forebrain, the preoptic area (POA) and mediobasal hypothalamus (MBH) at gestational day 14.5 (GD 14.5), a time when GnRH neurites grow towards the ME. Furthermore, in situ hybridization revealed that mRNA encoding the Shh receptor, Smoothened (Smo), was present in GnRH neurons from GD 15.5, when the first GnRH neurites are extending towards the MBH. In vitro neurite growth assays using hypothalamic explants from GD 15.5 fetuses in 3-D collagen gels showed that Shh was able to significantly stimulate GnRH neurite outgrowth. Finally, genetic deletion of Smo specifically from GnRH neurons in vivo, using Cre-loxP technology, resulted in a significant decrease in GnRH neurites innervating the ME. These experiments demonstrate that GnRH neurites use Shh for their neurite development, provide further understanding of the mechanisms by which GnRH nerve terminals arrive at their site of hormone secretion, and identify an additional hypothalamic neuronal population for which Shh/Smo signaling is developmentally important.

Traditional fiber reinforced polymer (FRP) composite that is often fabricated from single type of reinforcement has shown its ability to replace the conventional metallic material counterparts. However, due to several stringent requirements on ductility, this has affected the performance of FRP composites for the structural applications. Therefore, hybrid composites, which combine two or more fiber reinforcements, have been introduced in order to overcome the short of traditional FRP composites. This paper investigates the mechanical properties of three different arrangements of hybrid composites made from glass fiber (plain-woven and stitched bi-axial ±45˚) and plain-woven carbon fiber. Vacuum assisted resin transfer moulding method was employed to fabricate the hybrid composite panels. Mechanical properties such as tensile strength, flexural strength and volume fraction of the hybrid composites were determined per ASTM standards. Experimental results indicate that the [CWW] 6 arrangement, where C and W are weaved carbon fiber and glass fiber respectively, were superior in terms of mechanical properties.

A series of Zr50–Ti50 (at%) alloy specimens with different treatments was prepared. Tensile test, X-ray diffraction (XRD), optical microstructure, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses were performed to investigate alloy tensile properties and microstructure. Hot-rolling process was found to have a remarkable strengthening effect. The tensile strength of hot-rolled specimens had an increase of 37% compared with solution-treated specimen (undeformed). All specimens exhibited α′-Zr structures and similar microstructures. However, a significant plasticity difference was observed in the Zr50–Ti50 hot-rolled specimens with different cooling rates. Detailed TEM microstructural analysis showed that the morphology of twins in the hot-rolled specimens was different. Most of the twins were nano-twins. It was found that the twins had effective on Zr50–Ti50 alloy plasticity, in the meantime significant effects on tensile properties due to the complicated interactions between twin boundaries and dislocations. All these findings in this work may provide a new strengthening mechanism for Zirconium-based alloys.

Abstruct The microstructure evolution and mechanical properties response of a TZAV alloy during combined thermomechanical treatments containing hot rolling, cold rolling and subsequent annealing processes are investigated. Stress induced martensitic transformation presents after cold rolling and results in transformation from β to α ″ phase. Few peaks of ω phase were observed in specimens annealed below 650 °C. The microstructure of cold rolled and low temperature annealed specimens are characterized by stretched β grains and fibrous structures. While annealed at 700 °C, the specimen has most of approximate granular α grains. The average aspect ratio of α grains increases as the annealing temperature increases. After annealing at 800 °C, the stretched β grains recrystallize into approximate equiaxed grains. Tensile testing results showed that the deformed specimens have lower strength than annealed specimens. Hardness results showed the similar trend with strength. Otherwise, the relationships between microstructural parameters and mechanical properties are also discussed in this work. Results show that the strength is greatly dependent on thickness of α grains and content of β phase but has little to do with shape parameters of α grians, conversely, the ductility is related to shape parameters but independent of thickness and content.

The joining of titanium alloy to conventional structural steel has many industrial applications. However, it is difficult to join titanium alloys to steel due to great differences in thermal, physical, and chemical properties. Among these properties, the expansion coefficient is an important physical parameter. In this study, the expansion coefficient and mechanical properties of Ti–8Cu–5.7Al–3.8Zr (wt.%) alloy were studied. According to the experimental results, the eutectoid structure, which was composed of Ti 2 Cu and α phase, was observed in both air cooled and furnace cooled TiCuAlZr alloy after annealing at 800 °C. And the furnace cooled specimen revealed a more evident eutectoid structure. The results also showed that the difference of the average thermal expansion coefficients (−60 to 80 °C) between TiCuAlZr alloy and 9Cr18 martensitic stainless-steel were only 4%, which was beneficial to join titanium alloys to stainless steel. In addition, the air cooled specimen exhibited relatively good mechanical properties. The strength and the elongation were 1050 MPa and 8.5%, respectively.

The existing forms and effects of carbon on the surface structure and hardness of ZrTiAlV alloys with various Zr contents were investigated in this study. Each sample of ZrTiAlV–C alloys with Zr content below 17.3 at.% is composed of (TiZr)C compound, a few β phases, and matrix α phase. The Zr content in the compound increases with increased Zr content in alloys. At 17.3 at.% Zr content, both ZrC and (TiZr)C compounds are simultaneously observed. Only ZrC compound in addition to solid solutions is observed when the Zr content exceeds 17.3 at.%. Comparison of the XRD results of ZrTiAlV–C alloys with those of ZrTiAlV alloys shows that the addition of carbon to ZrTiAlV alloys can restrain the precipitation of Zr–Al compound. Microstructures show that the grain size of carbide in ZrTiAlV–C alloys decreases with increased Zr content. Hardness tests show that addition of carbon markedly affects the mechanical properties of ZrTiAlV alloys as the Zr content changes. The hardness of ZrTiAlV alloys with Zr content below 17.3 at.% gradually increases. However, a rapid decrease is observed when the Zr content is 25.95 at.%. Then, a plateau is observed when the Zr content ranges from 25.95 at.% to 60.55 at.%, and a rapid increase is observed when the Zr content is 69.2 at.%. However, the curve of hardness vs. Zr content of ZrTiAlV–C alloys is characterized as a parabola. The maximum hardness of ZrTiAlV–C alloys is 53.9 HRC when the Zr content is 43.25%. The maximum hardness increases by about 11% compared with the maximum hardness of ZrTiAlV alloys with various Zr contents. Otherwise, hardness tests also indicate that the strengthening effect of carbide on the β phase is better than that on the α phase.

A Heusler Ni 50 Mn 30 Ga 1 Cu 4 alloy with the highest compressive strength has been obtained by substituting 4 at% Cu for Ga in a ternary Ni 50 Mn 30 Ga 20 ferromagnetic shape memory alloy. It is shown that the highest compressive strength of 3178.9 MPa with a fracture strain up to 13.6% can be achieved at room temperature. To date, this is the highest compressive strength reported in the Ni–Mn–Ga alloy system. The martensitic structure changes from 7M with 0 at% Cu to non-modulated T martensite with 4 at% Cu . In addition, the Cu doping markedly increases the martensitic transformation temperature from 82.1 °C to 136.6 °C. At the same time, the Curie temperature and saturation magnetization for the Ni 50 Mn 30 Ga 16 Cu 4 alloy slowly decrease due to the 4 at% Cu addition.

The effect of partial substitution of Cu for Ga on the microstructure, martensitic transformation and mechanical properties of Ni 50 Mn 30 Ga 20− x Cu x alloys was investigated by optical microscope (OM), different scanning calorimetry (DSC) and X-ray diffraction (XRD). The results show that the Ni 50 Mn 30 Ga 20− x Cu x alloys exhibit thermoelastic martensitic transformation. The martensitic transformation temperatures of the Ni 50 Mn 30 Ga 20− x Cu x sample increase remarkably with increase of Cu content, while the martensite structure of these alloys changes from 7 M to non-modulated T martensite at room temperature. In addition, the compressive strength and fracture strain of alloys are clearly enhanced with increase of Cu content, which can be attributed to the strengthening of solution.

The structural evolution and mechanical properties of Zr–45Ti–5Al–3V alloy during heat treatment are investigated. X-ray diffraction (XRD) is used to analyze the alloy phase composition. The ω phase is detected after normalizing at 773 K and 873 K. The β-phase content increases with increasing holding temperature from 773 K to 973 K. The transmission electron microscopy (TEM) images of the microstructure shows that the thickness of the secondary αs phase is remarkably dependent on the cooling rate. The phase transformation is controlled by nucleation rate during cooling from low temperature 773 K and by growth velocity when cooled from high temperatures 973 K and 1073 K. The growth of the αs phase is very slow or stops when the temperature is cooled to 939.6 K. The thickness b of the αs phase of the Zr–45Ti–5Al–3V alloy relies on the onset transition temperature during cooling T0, and cooling rate υ has been deduced as b ( T 0 , υ ) = 0.019 ( T 0 − 939.6 ) / υ based on diffusion controlled growth mechanism. Tensile test results indicate that the strength of heat-treated Zr–45Ti–5Al–3V alloy is very sensitive to cooling rate.

Deformation of the bulk metallic glasses (BMGs) and the creation and propagation of the shear bands are closely interconnected. Shearing force was loaded on Zr41.2Ti13.8Cu12.5Ni10.0Be22.5(Vit.1) BMGs by cutting during the turning of the BMG rod. The temperature rise of alloy on the shear bands was calculated and the result showed that it could reach the temperature of the super-cooled liquid zone or exceed the melting point. The temperature rise caused viscous fluid flow and brought about the deformation of BMGs. This suggested that the deformation of BMGs was derived, at least to some extent, from the adiabatic shear temperature rise.

The effects of aging on magnetic properties and phase transformation were investigated for Ni 53 Mn 23.5 Ga 23 Ti 0.5 shape memory alloy. The results show that the amount and size of Ni 3 Ti particles firstly increase and then amount of second phase decreases with the increasing aging temperature. Moreover, the transformation temperatures gradually decrease; Curie temperatures slightly decrease first and reach their minimum values at 973 K then increase with the increasing aging temperature. The saturation magnetizations firstly remain almost unchanged and then slightly decrease when aging temperature is above 973 K.

The effect of Fe elements on the total energy of Ni 2 MnGa ferromagnetic shape memory alloy was investigated. It is shown that Fe addition has little effect on the majority-spin density of state (DOS), but changes minority-spin DOS significantly. Substituting Fe for Mn decreases the total DOS of the parent phase, leading to the increase in parent phase stability. When Fe content is higher than 12.5at%, the increasing of martensitic transformation is related to the precipitation of γ phase.

We report on the growth of unidirectional InN micropyramids by using a simple pattern-free epitaxial technique. These pyramids were grown on a GaN layer deposited on sapphire via metalorganic chemical vapor deposition (MOCVD). The XRD full width at half maximum (FWHM) was observed to be as low as 0.16° for the InN (0002) ω rocking curve which indicates very good crystal quality of these InN pyramids. The Photo-luminescence (PL) emission of InN micropyramids is ~0.78 eV. The dependency on growth conditions of pyramid density, facet stabilization, and pyramid structural quality have been evaluated and discussed.

The Ni53Mn23.5Ga18.5Ti5 ferromagnetic shape memory alloy has been aged under 2% constant-strain at various temperatures for 3 h, and the microstructure and martensitic transformation behaviors have been investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and differential scanning calorimetry (DSC). It was found that after constant-strain aging, the amount of the Ni-rich precipitates with lenticular morphology is higher and the size of the second-phase particle is smaller when compared to that of the conventional aged samples. The martensitic transformation temperatures first decrease remarkably with the increase of aging temperature, and then increase when the aging temperature exceeds 973 K, which can be attributed to the change of the Ni-content in the matrix as well as the strengthening effect by fine Ni3Ti precipitates.

In this paper, we present the computational task-management tool Ganga, which allows for the specification, submission, bookkeeping and post-processing of computational tasks on a wide set of distributed resources. Ganga has been developed to solve a problem increasingly common in scientific projects, which is that researchers must regularly switch between different processing systems, each with its own command set, to complete their computational tasks. Ganga provides a homogeneous environment for processing data on heterogeneous resources. We give examples from High Energy Physics, demonstrating how an analysis can be developed on a local system and then transparently moved to a Grid system for processing of all available data. Ganga has an API that can be used via an interactive interface, in scripts, or through a GUI. Specific knowledge about types of tasks or computational resources is provided at run-time through a plugin system, making new developments easy to integrate. We give an overview of the Ganga architecture, give examples of current use, and demonstrate how Ganga can be used in many different areas of science., Extended and clarified information on the Grid computing context for Ganga, supported job model etc. Additional minor corrections and clarifications. Updated the author list as agreed with the Ganga team

This paper presents a theoretical model to explain the quasi-supercontinuum interband emission from InGaAs/GaAs self-assembled semiconductor quantum dot lasers by accounting for both inhomogeneous and homogeneous optical gain broadening. The experimental and theoretical agreement of a room temperature (293 K) broadband laser emission confirms the presence of multiple-state lasing actions in highly inhomogeneous dot ensembles. The corresponding full-width half-maximum of the photoluminescence is 76 meV as opposed to those wideband lasing coverage at only low temperature (~60 K) from typical quantum dot lasers. A newly proposed change of homogeneous broadening with injection that occurs only in highly inhomogeneous quantum dot system is critical to account for the continuous wideband lasing but not the conventional ideas of carrier dynamics in semiconductor lasers. In addition, the analysis of threshold conditions reveals that broadband lasing only occurs when the energy spacing between quantized energy states is comparable to the inhomogeneous broadening of quantum-dot nanostructures. The study is important in providing a picture of this novel device and realization of broad lasing coverage for diverse applications, especially in the research field of short-pulse generation and ultra-fast phenomena in semiconductor quantum-dot laser.

The details of dynamic phenomena of broadband lasing in quantum-dot lasers in association with the role of both inhomogeneous and homogeneous optical gain broadening is theoretically investigated. The theoretical results of room temperature broadband laser signature are in well agreement with the experimental observation confirming the broadband stimulated emission from the laser is a result of the occurrence of multiple-state lasing in highly inhomogeneity quantum-dot systems.

We report on the development of InAs/InGaAlAs quantum-dash-in-well structure on InP substrate for wideband emitter applications. A spectral width as broad as 58 meV observed from both photoluminescence and surface photovoltage spectroscopy on the sample indicating the formation of highly inhomogeneous InAs-dash structure that results from the quasi-continuous interband transition. The two-section superluminescent diodes (SLDs), with integrated photon absorber slab as lasing suppression section, fabricated on the InAs dash-in-well structure exhibits the close-to-Gaussian emission with a bandwidth (full-width at half-maximum) of up to 140 nm at ~ 1.6 mum peak wavelength. The SLD produces a low spectrum ripple of 0.3 dB and an integrated power of ~ 2 mW measured at 20degC under 8 kA/cm2. The oxide stripe laser exhibits wide lasing wavelength coverage of up to 76 nm at ~ 1.64 mum center wavelength and an output optical power of ~ 400 mW from simultaneous multiple confined states lasing at room temperature. This rule changing broadband lasing signature, different from the conventional interband diode laser, is achieved from the quasi-continuous interband transition formed by the inhomogeneous quantum-dash nanostructure.

The design of high-rise building is often influenced by wind-induced motions such as accelerations and lateral deflections. Consequently, the building`s structural stiffness and dynamic (vibration periods and damping) properties become important parameters in the determination of such motions. The approximate methods and empirical expressions used to quantify these parameters at the design phase tend to yield values significantly different from each other. In view of this, there is a need to examine how actual buildings in the field respond to dynamic wind loading in order to ascertain a more realistic model for the dynamic behavior of buildings. This paper describes the findings from full-scale measurements of the wind-induced response of typical high-rise buildings in Singapore, and recommends an empirical forecast model for periods of vibration of typical buildings in Singapore, an appropriate computer model for determining the periods of vibration, and appropriate expressions which relate the wind speed to accelerations in buildings based on wind tunnel force balance model test and field results.

Induction of somatic embryogenesis from tissues in unopened flower buds of cocoa was studied with respect to physiological age, type of floral explant, genotype, and medium composition and phytohormones. Two-to-three-week-old staminodes were found to be the best explants for embryogenesis. Embryogenesis was affected by genotype and sugars. Two main types of abnormalities of the embryos were observed: fusion of the hypocotyls and multiple cotyledons. These embryos have a lower rate of conversion into plantlets. Cytological analyses of somatic embryo-regenerated plants revealed a somatic chromosome number of 2 n =2 x =20, similar to seed-derived plants.

We characterize size-dependent carrier relaxation dynamics of partial laser structures containing quantum dashes by time-resolved degenerate four wave mixing between 1.2 and 1.6 μm.

The temporal coherence functions of InGaAs-GaAs quantum-dot (QD) and InAs-InGaAlAs quantum-dash (Qdash) superluminescent diodes (SLDs) and broadband laser diodes (BLDs) are reported. Using an optical fiber-based spectral interferometer, the fabricated devices were shown to yield low coherence lengths of 4.00-12.29 mum and 33.48-74.56 mum for SLD and BLD devices, respectively. In addition, there were negligible secondary coherencies indicating that these devices have the potential for use in low coherent interferometric systems.

We demonstrate the effect of nonequilibrium carrier distribution in a self-assembled InAs-InAlGaAs quantum-dash-in-well semiconductor lasers on InP substrate. The progressive changes of electroluminescence spectrum with increasing injections show the presence of localized photon reabsorption and lasing action from different dash ensembles at room temperature as opposed to that obtained in typical self-assembled quantum-dot lasers only at low temperature below 100 K.

In this paper, the interaction between two identical, non-coplanar, semi-elliptical surface cracks is investigated. The interacting cracks are assumed to be in an infinite plate subjected to remote tension or to pure bending loads. The stress intensity factors (SIFs) for these cracks are calculated using three-dimensional linear finite element analysis. A parametric study involving the relative horizontal and vertical separation distance between the two surface cracks is carried out for a specific crack shape and crack depth to plate thickness ratios of 0.3 and 0.2, respectively. An empirical formula is derived that relates the effects of the relative positions of these cracks to their SIFs.

Gain and alpha factors were measured on InAs-InAlGaAs quantum-dash lasers with their heterostructures intermixed by either a dielectric-capping or ion-implantation technique. The laser intermixed by the dielectric-capping technique exhibits a blue shift as much as 93 nm without degrading the laser quality. In comparison, the laser intermixed by the ion-implantation technique has a larger shift but lower differential gain and higher alpha factor. The result implies that quantum-dash lasers of different wavelengths can be effectively integrated on the same chip by the dielectric-capping intermixing technique.