Great Number Of Experimental Data Research Articles

Experimental Investigation on Pedestrian Walking Load in Steel Footbridges

Accurate simulation of walking load is of great significance in conducting human-induced vibration analyses. However, accurate pedestrian walking load data obtained from long-span footbridges is scarce and data reliability depends on the sensor used for measurement. In the current work, Yanluo Footbridge with 102 m span was adopted as test site and Xnode high-precision acceleration wireless sensor was applied for measurements. An experimental investigation was performed on walking loads according to bipedal walking force model. In experimental studies, single-person and multi-person walking tests were performed at Yanluo Footbridge to measure corresponding stride frequency and dynamic load factor. The acceleration time-histories of walking pedestrians were accurately recorded using three-axis wireless acceleration sensor Xnode. Furthermore, the equation of dynamic load factor was derived by analyzing time-histories and power spectra and the design models of pedestrian walking load and crowd load were developed based on a great number of experimental data. Time histories of pedestrian walking loads showed regular periodic changes and dynamic load factor increased by increasing stride frequency. Using the walking load model developed in this work, the reliable structure response of human-induced vibration analysis can be obtained.

Empirical equations between characteristic impedance and mechanical properties of rocks

Abstract Based on a great number of experimental data on various mechanical properties of rock in the literature, six empirical equations between the characteristic impedance (product of density and P-wave velocity) and mechanical properties of rock are proposed. These properties include uniaxial compressive strength, tensile strength, shear strength, mode I fracture toughness, Young's modulus, and Poisson's ratio. These empirical equations show that the values of the aforementioned properties increase with increase in characteristic impedance. It also implies that the characteristic impedance of rock may be considered as an index to represent the main properties of rock. In this sense, it is possible to consider using characteristic impedance to classify rock masses for studies in the future.

Sampling method for the determination of methane emissions from landfill surfaces.

The first aim of this work is the definition and the study of a suitable sampling method for the measurement of landfill gas (LFG) emissions from landfill surfaces, since, up to now, there are no codified nor universally accepted sampling methods for this specific task. The studied sampling method is based on the use of a static hood. The research work involves a preliminary theoretical study for the hood design, experimental tests for the definition of the optimal sampling procedures, and simulations of the hood fluid-dynamics for the system validation. The second aim of this study is the investigation of the correlations between LFG emissions and meteorological conditions, whose identification would be very useful in terms of effective landfill management and pollution control. This involved a wide literature study for the selection of those parameters that seem to have an influence on LFG emission, and the collection of a great number of experimental data on a target site, which led to the conclusion that atmospheric pressure and soil humidity are the parameters that mostly affect LFG emissions.

Screening of Carotenoids in Tomato Fruits by Using Liquid Chromatography with Diode Array-Linear Ion Trap Mass Spectrometry Detection.

This paper presents an analytical strategy for a large-scale screening of carotenoids in tomato fruits by exploiting the potentialities of the triple quadrupole-linear ion trap hybrid mass spectrometer (QqQLIT). The method involves separation on C30 reversed-phase column and identification by means of diode array detection (DAD) and atmospheric pressure chemical ionization-mass spectrometry (APCI-MS). The authentic standards of six model compounds were used to optimize the separative conditions and to predict the chromatographic behavior of untargeted carotenoids. An information dependent acquisition (IDA) was performed with (i) enhanced-mass scan (EMS) as the survey scan, (ii) enhanced-resolution (ER) scan to obtain the exact mass of the precursor ions (16-35 ppm), and (iii) enhanced product ion (EPI) scan as dependent scan to obtain structural information. LC-DAD-multiple reaction monitoring (MRM) chromatograms were also acquired for the identification of targeted carotenoids occurring at low concentrations; for the first time, the relative abundance between the MRM transitions (ion ratio) was used as an extra tool for the MS distinction of structural isomers and the related families of geometrical isomers. The whole analytical strategy was high-throughput, because a great number of experimental data could be acquired with few analytical steps, and cost-effective, because only few standards were used; when applied to characterize some tomato varieties ('Tangerine', 'Pachino', 'Datterino', and 'Camone') and passata of 'San Marzano' tomatoes, our method succeeded in identifying up to 44 carotenoids in the 'Tangerine'" variety.

ChemInform Abstract: Chemical and Physical Interactions Between Metal and Oxidic Supports in Catalytic Systems

Abstract The importance of the metal-support interaction on the catalytic properties of an oxide-supported metal has been shown by a great number of experimental data. Structural, chemical and electronic interactions are all very important to realize the catalyst configuration responsible for its high reactivity and/or selectivity. Furthermore the interactions can become more important during the catalytic process itself, and new surface characteristics can be developed. In this paper we examine, with selected examples, the different aspects of the interaction, how they are correlated and how they can be evidenced by different techniques and more specifically by IR or FT-IR spectroscopy.

Epigenetically regulated tumor-associated antigens in melanoma

Surgical resection represents the treatment of choice for primary melanoma, providing the best results, in terms of long-term survival, for thin lesions. However, surgery has limited efficacy in the management of locoregional and distant metastases, as do chemotherapy and radiotherapy. In this context, immunotherapy is a promising and additional therapeutic option to cure melanoma patients and to prevent relapse of the disease. The identification and characterization of immunogenic tumor-associated antigens (TAAs) has prompted the design and development of a plethora of therapeutic vaccines to drive the host immune system to specifically recognize and eradicate neoplastic cells. Although encouraging, clinical results obtained with TAA-based vaccination are not yet satisfactory. In this regard, a great number of experimental data indicate that neoplastic cells are capable of escaping the host’s immune surveillance and impairing the efficacy of immunotherapeutic approaches by different mechanisms. Among the...

Reggeon, Pomeron and Glueball, Odderon-Hadron-Hadron Interaction at High Energies — From Regge Theory to Quantum Chromodynamics

Based on analysis of scattering matrix S, and its properties such as analyticity, unitarity Lorentz invariance, and crossing symmetry relation, the Regge theory was proposed to describe hadron-hadron scattering at high energies before the advent of QCD, and correspondingly a Reggeon concept was born as a mediator of strongly interaction. This theory serves as a successful approach and has explained a great number of experimental data successfully, which proves that the Regge theory can be regarded as a basic theory of hadron interaction at high energies and its validity in many applications. However, as new experimental data come out, we have some difficulties in explaining the data. The new experimental total cross section violates the predictions of Regge theory, which shows that Regge formalism is limited in its applications to high energy data. To understand new experimental measurements, a new exchange theory was consequently born and its mediator is called Pomeron, which has vacuum quantum numbers. The new theory named as Pomeron exchange theory which reproduces the new experimental data of diffractive processes successfully. There are two exchange mediators: Reggeon and Pomeron. Reggeon exchange theory can only produce data at the relatively lower energy region, while Pomeron exchange theory fits the data only at higher-energy region, separately. In order to explain the data in the whole energy region, we propose a Reggeon–Pomeron model to describe high-energy hadron-hadron scattering and other diffractive processes. Although the Reggeon–Pomeron model is successful in describing high-energy hadron-hadron interaction in the whole energy region, it is a phenomenological model. After the advent of QCD, people try to reveal the mystery of the phenomenological theory from QCD since hadron-hadron processes is a strong interaction, which is believed to be described by QCD. According to this point of view, we study the QCD nature of Reggeon and Pomeron. We claim that the Reggeon exchange is an exchange of multigluon, the color singlet gluon bound state. In particular, the Pomeron could be a Reggeized tensor glueball ξ(2230) with mass of 2.23 GeV, quantum numbers IG, JPC = 0+, 2++ and decay width of about 100 MeV. The glueball exchange theory reproduces data quite well. Accordingly, we believe that the Odderon, consisting of three Reggeized gluons, and predicted by QCD, should also contribute to hadron-hadron scattering and many other diffractive processes. We search for the Odderon by studying p̄p and pp elastic scatterings at high energies. Our investigations on the differential cross section dσ/dt of hadron-hadron scattering at various energies and comparisons with experimental data show that the Odderon plays an essential role in fitting to data. Therefore, we suggest that the measurements should be urgently done in order to confirm the existences of the Odderon and to test QCD.

Desorption characteristics of coalbed methane reservoirs and affecting factors

The desorption characteristics of coalbed in China are affected by many factors. The desorption ratio of coalbed gas is approximately 40%, and mostly less than 70%, and it is affected by gas content and coalbed pressure. Most of the desorption time values are between 0.1883 and 19.17d, and the time span of high-rank coal is the highest, which can reach 30 d. The value has a positive correlation with coal rank. A great number of experimental data show that temperature, coal dimension and shape, coal rank, ash content, gas content, cleat, sediment environment, and coal style are the main factors affecting desorption time. According to the numerical simulation result, coal desorption volume affects the single well production. And the single well output has a positive correlation with the desorption. The variation of coal desorption time value can induce the change of output peak value of a single well and its occurrence time.

Cleavag Fracture Criterion of Low Alloy Steal and Weld Metal in Notched Specimens

The cleavage fracture criterion of low alloy steel and weld metal in notched specimens is investigated in detail based on a great number of experimental data. It has been found that the most cleavage fractures initiate at a distance shorter (left side) than that of the peak stress location below a notch root, and the cleavage fracture in notched specimens must satisfy a dual criterion, i.e., a critical plastic strain (ep ≥ epc) for initiating a crack nucleus, and a critical tensile stress (σyy ≥ σf) for its propagation. According to the dual criterion model, the great number of experimental data of 4PB (four-point bending) tests for the low alloy steel and weld metal and their statistical distribution are explained. The effects of temperature , the local fracture stress σf and the critical plastic strain epc on the locations of cleavage initiation sites and the controlling steps of cleavage fracture process are discussed.

R-Line Thermal Shift and Thermal Broadenings of R, R′ and B Lines for Ruby**The project partly supported by National Natural Science Foundation of China, Grant No. 19744001

The unified theoretical calculation of thermal shifts (TS) of R1 and R2 lines and thermal broadenings (TB) of R, R′ and B lines for ruby was carried out for the first time. The calculated results are in very good agreement with a great number of experimental data. Especially, by using quantum theory and taking into account all the admixtures of wavefunctions within d3 electronic configuration, all the ΓM in electron-phonon interaction (EPI), the electronic energy spectrum and lattice-vibration Spectrum, the very important contributions to TS and TB from single-phonon direct process were theoretically calculated in detail. The microscopic essentials of various contributions are revealed, and the mistakes in previous work are remedied.

Pressure-induced shifts of energy levels ofα−Al2O3:V3+and a complete ligand-field calculation

An improvement of ligand-field theory has been developed. Based on our theory of pressure-induced shifts and the diagonalization of the complete energy matrix, the unified calculation of the whole energy spectrum and $g$ factors of the ground state at normal pressure and their pressure-induced shifts has been carried out. All the calculated results for $\ensuremath{\alpha}\ensuremath{-}{\mathrm{Al}}_{2}{\mathrm{O}}_{3}{:\mathrm{V}}^{3+}$ are in very good agreement with a great number of experimental data. It is found that the distinct differences in magnitude and/or sign for pressure-induced shifts of various levels are immediately determined by characteristic dependencies of levels on the parameters of interactions, and the pressure-induced shifts of levels can provide definite or crucial criteria for the correctness of assignments and calculations of them.

The increase in peak strength and strain in confined concrete for a wide range of strengths and degrees of confinement

By statistically processing a great number of experimental data (about 130) from the literature, we have pointed out that the main relations proposed by various authors to express the increase in strength and strain of concrete at the peak due to confinement agree with the physical reality only if parameters involved over a limited range are included.

Determination of a polarizability index by means of a molecular topology

The polarizability of the molecule is an important property to account for molecular interactions. Different polarizability indices have been proposed all based on the knowledge of the refraction index. This property is not always easily obtained at room temperature in the liquid state. In the present study, a topological method (i.e., only based on structure) is proposed, validated by a great number of experimental data. Also the molar volume at the boiling point has been estimated in a topological way.

Investigation on onset of shock-induced separation

A great number of experimental data indicating shock wave/boundary layer interactions in internal or external supersonic flows were reviewed to make clear the mechanism of the interaction and to decide the onset of shock-induced separation. The interesting conclusions were obtained for the considerably wide range of flow geometries that the onset of separation is independent of the flow geometries and the boundary layer Reynolds number. It is found that the pressure rise necessary to separate the boundary layer in supersonic external flows could be applied to such internal flows as overexpanded nozzles or diffusers. This is due to the fact that the separation phenomenon caused by shock wave/boundary layer interactions is processed through a supersonic deceleration. The shock-induced separation in almost all of interacting flow fields is governed by the concept of free interaction, and the onset of shock-induced separation is only a function of the Mach number just upstream of shock wave. However, physical scales of the produced separation are not independent of the downstream flow fields.

The Combustion of Droplets Within Gas Turbine Combustors: Some Recent Observations on Combustion Efficiency

For many years investigators studying the combustion behavior within gas turbines have presumed droplet size to play a very important role in defining combustion efficiency. Recently a very large number of experiments have been conducted jointly by Laval University and the Aeronautical Research Laboratory in Melbourne. In the course of these investigations, over a wide range of operating conditions, a single combustor has been investigated using three different Simplex atomizers at each of the conditions for three fuels. In addition, the same combustor has been used to investigate a very wide range of fuels (87) at ambient inlet conditions. The measured combustion efficiencies show no measurable effects due to droplet size, although volatility effects have been noted (measured as TAV). It is thought that these effects are reflected in terms of a transfer number and related to diffusional phenomena, rather than evaporative phenomena. A great number of experimental data are reviewed, and in addition to showing the absence of effects of droplets, a small section deals with the precision of experimental values of combustion efficiency and how it might influence models predicting combustion efficiency, especially with respect to possible future pollution requirements.

Chemical and physical interactions between metal and oxidic supports in catalytic systems

The importance of the metal-support interaction on the catalytic properties of an oxide-supported metal has been shown by a great number of experimental data. Structural, chemical and electronic interactions are all very important to realize the catalyst configuration responsible for its high reactivity and/or selectivity. Furthermore the interactions can become more important during the catalytic process itself, and new surface characteristics can be developed. In this paper we examine, with selected examples, the different aspects of the interaction, how they are correlated and how they can be evidenced by different techniques and more specifically by IR or FT-IR spectroscopy.

Gaussian ϕ(ρz) curves: Comparison with other models

X ray characteristic intensity Ii , emerging from element i in a bulk sample irradiated with an electron beam may be obtained throughwhere the function ϕi(ρz) is the distribution of ionizations for element i with the mass depth ρz, ψ is the take-off angle and μi the mass absorption coefficient to the radiation of element i.A number of models has been proposed for ϕ(ρz), involving several features concerning the interaction of electrons with matter, e.g. ionization cross section, stopping power, mean ionization potential, electron backscattering, mass absorption coefficients (MAC’s). Several expressions have been developed for these parameters, on which the accuracy of the correction procedures depends.A great number of experimental data and Monte Carlo simulations show that the general shape of ϕ(ρz) curves remains substantially the same when changing the incident electron energy or the sample material. These variables appear in the parameters involved in the expressions for ϕ(ρz). A good description of this function will produce an adequate combined atomic number and absorption correction.

A General Rate Equation for Nuclear Waste Glass Corrosion

AbstractA general rate equation was developed to describe the reaction of nuclear waste glasses with aqueous solutions as a function of pH, the ratio of sample surface area to solution volume, temperature, time, glass- and solution composition. Thermodynamic and kinetic models have been combined in a new model. Glass network dissolution, pH variation, precipitation of stable or metastable solid reaction products, silica saturation at the glass and solution interface (reaction zone) and a residual affinity for the long term reaction under near saturation conditions have been addressed. The model has been successfully used to interpret a great number of experimental data reported in literature.