Core Column Research Articles

A Massive Structured Data Storage Technology for Commodity Screening Applications

With the rapid development of e-commerce, the number of goods has become more and more. When commodity screening system is used to store and process mass information, the existing models require all nodes in the distributed system to work in parallel, then the results of each node are integrated to get the final results, the process produces a lot of invalid queries. In order to solve this problem, proposed a new distributed structured data storage method. It statistics the history search results and chooses the high frequency or core columns to be key columns. The data can be stored based key columns and distribute system architecture. Then in the searching stage, only some nodes work when the search refer to key columns. The results show that this method can reduce the tasks and improve the throughout without extra storage consumption.

Terrestrial n-alkanes and their carbon isotope records from the Hanon paleo-maar sediment, Jeju Island, Korea: Implications for paleoclimate and paleovegetation over the last 35 kyrs

The carbon isotope of total carbon (δ13Corg), long-chain n-alkanes, and their compound-specific carbon isotope ratios (δ13CALK) were investigated in the Hanon paleo-maar sediment, Jeju Island of Korea to understand paleoclimate variabilities and their paleovegetation linkages. Based on the organic geochemical data (TOC (%), TN (%), and their δ13Corg and δ15N), the core column stratigraphy was divided into three units, namely from the bottom to 14.5 ka (Unit I), from 14.5 ka to 3.0 ka (Unit II), and from 3.0 ka to the core top (Unit III), respectively. In particular, δ13Corg showed marked fluctuation from −17.31‰ to −28.68‰, suggesting different organic carbon sources. A relatively narrow range of variation in δ13Corg was observed in Unit III, and drastic changes in δ13Corg were observed from Unit I to Unit II. This may indicate a predominance of C4 plants in Unit I, and drastic changes from terrestrial C4 to C3 in Unit II and predominance of C3 plants in Unit III. The distributions of n-alkane were characterized by a continuous predominance of odd-numbered n-alkanes, particularly nC29 and nC31, and by high fluctuation of the total n-alkanes concentration. The average chain length (ACL), carbon preferences index (CPI), and paleo-plant proxy (Paq) showed high fluctuation and glacial-interglacial variations with distinctive a high and low ratio at about 9.2 ka, corresponding to the switching points of δ13Corg and a high concentration of n-alkane distribution. Individual n-alkane odd-numbered isotopes of δ13CALK ranged between −11.80‰ in δ13nC21 and -34.93‰ in δ13nC31, suggesting different sources of n-alkanes. The distribution of n-alkanes and their individual δ13CALK, in particular δ13nC21, support paleovegetation changes, and their time-dependent variations matched well with glacial-interglacial paleoclimate variations. Therefore, organic geochemical proxies recorded in Hanon paleo-maar sediment reflects paleoclimate variabilities as well as paleovegetation changes for the last 35 kyr in Jeju Island, Korea.

Stress-transfer in concrete encased and filled tube square columns employed in top-down construction

Top-down construction is a construction technique in which pit excavation and structure construction are conducted simultaneously. Reducing construction time and minimizing noise and vibration which affect neighboring structures, the technique is widely employed in constructing downtown structures. While H-steel columns have been commonly used as core columns, concrete filled steel tube (CFT) columns are at the center of attention because the latter have less axial directionality and greater cross-sectional efficiency than the former. When compared with circular CFT columns, square CFT columns are more easily connected to the floor structure and the area of percussion rotary drilling (PRD) is smaller. For this reason, square CFT columns are used as core columns of concrete encased and filled square (CET) columns in underground floors. However, studies on the structural behavior and concrete stress transfer of CET columns have not been conducted. Since concrete is cast according to construction sequence, checking the stress of concrete inside the core columns and the stress of covering concrete is essential. This paper presents the results of structural tests and analyses conducted to evaluate the usability and safety of CET columns in top-down construction where CFT columns are used as core columns. Parameters in the tests are loading condition, concrete strength and covering depth. The compressive load capacity and failure behavior of specimens are evaluated. In addition, 2 cases of field application of CET columns in underground floors are analyzed.

Axial loading capacity of concrete‐jacketed RC columns with pre‐ and post‐corrosion damage

AbstractThe main objective of this study is to investigate the effect of pre‐ and post‐jacketing corrosion and loading damage on concrete‐jacketed reinforced concrete (RC) columns under uniaxial loading and to develop a methodology for predicting the corresponding compressive strength. The pre‐ and post‐damage involved preloading up to 50 % of the peak load of the core column, an electrochemical process to accelerate the migration of chlorides from an external electrolyte into the test columns and a wetting–drying cycle process with a controlled current to speed up the corrosion of the steel reinforcing bars in the test columns. Uniaxial loading tests were performed to determine the structural performance of the concrete‐jacketed columns with and without corrosion damage. The failure mode and load–displacement and load–strain responses of the test columns were recorded, and the related mechanisms are discussed. A model capable of evaluating the compressive strength of unjacketed or jacketed RC columns with and without corrosion damage was then developed. The analytical approach considered the effect of reinforcement corrosion on the effective loadbearing area of the concrete and the confinement effect of the stirrups. The analytical results agree well with the experimental results, indicating the reliability and effectiveness of the models developed.

The JCMT andHerschelGould Belt Surveys: a comparison of SCUBA-2 andHerscheldata of dense cores in the Taurus dark cloud L1495

We present a comparison of SCUBA-2 850-$\mu$m and Herschel 70--500-$\mu$m observations of the L1495 filament in the Taurus Molecular Cloud with the goal of characterising the SCUBA-2 Gould Belt Survey (GBS) data set. We identify and characterise starless cores in three data sets: SCUBA-2 850-$\mu$m, Herschel 250-$\mu$m, and Herschel 250-$\mu$m spatially filtered to mimic the SCUBA-2 data. SCUBA-2 detects only the highest-surface-brightness sources, principally detecting protostellar sources and starless cores embedded in filaments, while Herschel is sensitive to most of the cloud structure, including extended low-surface-brightness emission. Herschel detects considerably more sources than SCUBA-2 even after spatial filtering. We investigate which properties of a starless core detected by Herschel determine its detectability by SCUBA-2, and find that they are the core's temperature and column density (for given dust properties). For similar-temperature cores, such as those seen in L1495, the surface brightnesses of the cores are determined by their column densities, with the highest-column-density cores being detected by SCUBA-2. For roughly spherical geometries, column density corresponds to volume density, and so SCUBA-2 selects the densest cores from a population at a given temperature. This selection effect, which we quantify as a function of distance, makes SCUBA-2 ideal for identifying those cores in Herschel catalogues that are closest to forming stars. Our results can now be used by anyone wishing to use the SCUBA-2 GBS data set.

Energy absorption characteristics of diamond core columns under axial crushing loads

The energy absorption characteristics of diamond core sandwich cylindrical columns under axial crushing process depend greatly on the amount of material which participates in the plastic deformation. Both the single-objective and multi-objective optimizations are performed for columns under axial crushing load with core thickness and helix pitch of the honeycomb core as design variables. Models are optimized by multi-objective particle swarm optimization (MOPSO) algorithm to achieve maximum specific energy absorption (SEA) capacity and minimum peak crushing force (PCF). Results show that optimization improves the energy absorption characteristics with constrained and unconstrained peak crashing load. Also, it is concluded that the aluminum tube has a better energy absorption capability rather than steel tube at a certain peak crushing force. The results justify that the interaction effects between the honeycomb and column walls greatly improve the energy absorption efficiency. A ranking technique for order preference (TOPSIS) is then used to sort the non-dominated solutions by the preference of decision makers. That is, a multi-criteria decision which consists of MOPSO and TOPSIS is presented to find out a compromise solution for decision makers. Furthermore, local and global sensitivity analyses are performed to assess the effect of design variable values on the SEA and PCF functions in design domain. Based on the sensitivity analysis results, it is concluded that for both models, the helix pitch of the honeycomb core has greater effect on the sensitivity of SEA, while, the core thickness has greater effect on the sensitivity of PCF.

Numerical study on load transfer effect of Stiffened Deep Mixed column-supported embankment over soft soil

A new composite column technique referred to as Stiffened Deep Mixed (SDM) column has been adopted to support embankment over soft soil to mitigate the post-construction settlement, increase bearing capacity and enhance stability. The SDM column was formed by inserting a precast concrete core pile into the center of a Deep Mixed (DM) column immediately after the construction of DM column. Due to the complicate interaction between concrete core pile, DM column and surrounding soil, the load transfer mechanism between SDM column and surrounding soil has not been well understood yet. This paper presents a series of three- Dimensional (3-D) finite-element analyses to investigate the load transfer effect of SDM column-reinforced ground under embankment. First, the numerical method was validated by a comparison with field data in terms of settlements and vertical stress on the head of SDM column. Then, based on the validated simulation method, the 3-D numerical model of the SDM column-supported embankment over soft soil was established, and the influence factors of length of DM column and concrete core pile, cross section area of concrete core pile, column spacing and embankment height on the load transfer effect were investigated, respectively. The results showed that the column spacing and height of embankment fill had significant effects on the load transfer between SDM column and surrounding soil, while the influences of length of DM column and concrete core pile, and cross section area of concrete core pile on the load transfer effect were minor. Finally, four current commonly-used design methods were assessed in the prediction of the efficacy of SDM-reinforced soil under embankment loading. The current commonly-used design methods showed great differences in the load transfer predictions of the SDM column-supported embankment over soft soil due to the existence of outer DM column socket. A modified method was proposed for the use of EBGEO (2011) in the design of SDM column-supported embankment over soft soil.

Dynamic Responses of RPC-Filled Steel Tubular Columns Post Fire Under Blast Loading

Blast-resistant capacities of 4 large scale circular Reactive Powder Concrete Filled Steel Tubular (RPC-FST) columns after exposure to fire are experimentally examined. The overpressures of shock wave, the deflections and strains of RPC-FST column specimens are recorded by advanced gauges. The influences of fire durations and scaled standoff distances of explosive charge on the dynamic behaviors and failure modes are discussed. It is shown that the RPC-FST columns remain excellent blast-resistant capacities after exposure to fire. RPC core column can be effectively confined by steel tube, but the blast-resistant capacities of RPC-FST columns are decreased as explosive charge or fire duration increased. The failure modes are transited from bending types to bending-shear types as explosive charge increased, and an obvious plastic hinge at mid-span section can be observed in the RPC-FST column with fire duration of 105min. It is also indicated that the maximum displacements of RPC-FST columns are more sensitive to fire duration than to explosive charge weight.

Stability-indicating UHPLC method for determination of nevirapine in its bulk form and tablets: identification of impurities and degradation kinetic study

Nevirapine (NVP), a non-nucleoside reverse transcriptase inhibitor, is a drug widely used in the treatment of Acquired Immunodeficiency Syndrome (AIDS). The evaluation of NVP stability is of fundamental importance in order to guarantee drug product efficacy, safety and quality. In this study, NVP active pharmaceutical ingredient (API) and tablets were subjected to a detailed study of forced degradation, employing several degrading agents (acid, alkaline, water, metal ions, humidity, heat, light and oxidation agents). In order to determine NVP and the degradation products formed, a stability-indicating UHPLC method using fused core column was developed and validated. The separation was carried out using a Poroshell 120C18 column (100×2.1mm i.d.; 2.7μm particle size) and the mobile phase was composed of acetonitrile and water in a gradient elution, at a flow rate of 0.2ml/min. Chemical structures and mechanisms for the formation of three degradation products were proposed by means of LC/MS-MS. Also, NVP degradation kinetic was studied and its order of degradation evaluated. NVP was degraded in acidic and oxidative conditions and the degradation profile for NVP tablets and API were similar. The stability-indicating method proved to be selective for NVP and its degradation products. Calibration curve was linear in the range of 8–48μg/ml and the method showed to be precise, accurate and robust for both NVP API and tablets, with detection and quantification limits of 0.092μg/ml and 0.174μg/ml, respectively.

Near-field blast test on reactive powder concrete-filled steel tubular columns after exposure to fire

The existing blast tests of concrete-filled steel tubular are mainly on the dynamic behaviors of concrete-filled steel tubular at ambient temperature. ANSYS codes are used to simulate the temperature distribution of reactive powder concrete-filled steel tubular, and subsequently an approximate approach is used to estimate the residual strength of reactive powder concrete. Then blast-resistant capacities of four large-scale reactive powder concrete-filled steel tubular columns after exposure to ISO-834 standard fire are experimentally examined. The overpressures of shock wave, displacements, and strains of reactive powder concrete-filled steel tubular columns are recorded by advanced gauges. Influences of fire durations and scaled stand-off distances of explosive charge on dynamic behaviors and failure modes of reactive powder concrete-filled steel tubular columns are discussed. It is shown that reactive powder concrete-filled steel tubular columns retain excellent blast-resistant capacity after exposure to fire. Reactive powder concrete core column can be effectively confined by steel tube, but its blast-resistant capacity decreases as explosive charge or fire duration increases. Failure modes change from bending types to bending-shear types as explosive charge increases, and obvious plastic deformation at the mid-span section can be observed in the reactive powder concrete-filled steel tubular columns with fire duration of 105 min. It is also indicated that the maximum displacement of reactive powder concrete-filled steel tubular columns is more sensitive to fire duration than to explosive charge weight.

A Rapid Method for the Analysis of Paralytic Shellfish Toxins Utilizing Standard Pressure HPLC: Refinement of AOAC 2005.06.

Superficially porous column technologies have previously been shown to provide faster chromatographic analysis of toxin oxidation products when analyzing shellfish for paralytic shellfish toxins. While sub 3 μm fused core columns have facilitated enhanced method performance, including significantly lower analysis times and lower LOD, they were also found to last for only a few hundred injections before pressure increases rendered them unusable with standard HPLC. Recently 5 μm superficially porous columns have become commercially available. In this study, a 5 μm fused core column was used to develop a fast chromatographic method for the analysis of paralytic shellfish toxins, with performance characteristics and column lifetime being assessed. The 5 μm column was found to be able to perform approximately 3000 injections without significant increases in back pressure or reduction in performance. Data generated using the column were found to be equivalent to that determined using current HPLC column technologies for both screening and quantitation methods. Furthermore, an increase in sensitivity for all toxins tested under the routine monitoring program for British waters was observed and the overall run time of the analysis halved. Overall, the 5 μm fused core column provided a significant increase in sample throughput, a reduction in mobile phase consumption, and an increase in method sensitivity.

E-Cored Coil With a Circular Air Gap Inside the Core Column Used in Eddy Current Testing

The problem of an axially symmetric E-cored coil with a circular air gap inside the core column located above a two-layered conductive half-space is presented. The truncated region eigenfunction expansion method is used to derive expressions describing the magnetic vector potential of the filamentary coil. The final expressions for the impedance of the rectangular cross-sectional coil are obtained, and calculations for various frequency values are carried out. The results are compared with those from the COMSOL package, which shows a very good agreement.

Fire safety assessment of super tall buildings: A case study on Shanghai Tower

Shanghai Tower is an existing super high-rise building composed of mega frame-core-outrigger lateral resisting systems. Its structural safety in fire has been given great attention. This paper presents an independent review of the performance of Shanghai Tower in case of fire. Two fire scenarios: standard fires and parametric fires have been considered. The fire resistance of key component, including the concrete core, mega columns, the composite floor, outrigger trusses and belt trusses were examined first. Their real fire resistance periods proved to be far beyond the design fire resistance. The components with weak fire resistance such as peripheral steel columns and web members of belt trusses were then removed to study the resistance of the residual structure against progressive collapse. The results show that Shanghai Tower has a minimum of 3h fire resistance against fire-induced progressive collapse. The concrete components have smaller residual displacements compared to the steel components. It is recommended, for the design of other similar structures, that effective fire protection should be provided for the outrigger trusses to guarantee the connection between the core and mega columns.

Determination of free and bound phenolic compounds in soy isoflavone concentrate using a PFP fused core column

In the last years, the consumption of soy-based foods has increased due to the health benefits related to soy bioactives like phenolic compounds. Thus, in the present study, a new chromatographic method using reverse-phase high performance liquid chromatography coupled to diode array detection (RP-HPLC/DAD) was developed using a fused core pentafluorophenyl (PFP) column. The established method allowed the determination of twenty-one free phenolic compounds and eleven bound phenolics in a soy isoflavone concentrate.The method was validated in terms of precision and recovery. Intra and inter-day precision were less than 5% (% RSD) and the recovery was between 97.4% and 103.6%. Limits of quantification (LOQs) ranged between 0.093 and 0.443μg/mL.Because of that, PFP stationary phase can be easily applied for routine determination of phenolic compounds in soy based foods.

Hydrophobic associated polymer based silica nanoparticles composite with core–shell structure as a filtrate reducer for drilling fluid at utra-high temperature

Abstract Nano or micro-nano-based materials have attracted a strong interest due to its attractive properties and they have great potential for developing intelligent drilling fluid in petroleum industry. In this article, a novel hydrophobic associated polymer based silica nanoparticles composite with core–shell structure which was mainly used for developing intelligent drilling fluid additive for drilling ultra-deep well under ultra-high temperature, ultra-high pressure and salinity, was prepared with Acrylamide, 2-Acrylamide-2-methylpro pane sulfonic acid, Maleic anhydride, Styrene and silica nanoparticles via inverse micro emulsion polymerization and sol–gel preparation, and was characterized by particle size distribution, SEM, TEM ESEM and the influence law of comprehensive performance of water based drilling fluid and its mechanism influenced by novel hydrophobic associated polymer based silica nanoparticles composite were studied too. Micro-model drilling fluid flooding and drilling fluid displacement experiment of core column were adopted to assess the plugging stability of micro-pores and micro-cracks and effect on wellbore stability. The experimental data showed that, the composite as a micro-nano-drilling fluid additive, possessed excellent properties such as thermal stability, rheology, fluid loss and lubricity. Especially, it could plug the formation effectively and improve the pressure bearing capability of formation significantly.

An approach to improve conventional square ferrocement jacket for strengthening application of short square RC column

The confinement effect over the cross-section of a square column is non-uniform compared to the same of a circular column. Concentration of stresses and subsequent cracking in the confining external jacket occurs at the corners of a square column; and thus the effectiveness of external jacket in such column is reduced significantly. The conventional square ferrocement jacket consists of rich mix cement mortar with single or multiple layers of wire mesh. This type of external jacket also experience similar problems in confining core columns. This study aims to develop efficient techniques to overcome the drawbacks of conventional square ferrocement jackets in strengthening of short square-shaped RC columns. Three techniques and variations in those techniques are proposed to address the problem. Experimental studies of selected variation from each technique affirm the effectiveness of the proposed techniques in addressing the problem associated with conventional square ferrocement jackets. The experimental investigation reveals that all the retrofitted square ferrocement-jacketed short columns exhibit higher load carrying and deflection capacities before failure compared with non-jacketed as well as conventional square ferrocement-jacketed columns. The findings indicated that the proposed techniques are efficacious to address the problem of conventional square ferrocement jacket.

Applications and Analysis of the Composite wall on Construction in Heilongjiang Province

Applications and Analysis of the Composite wall on Construction in Heilongjiang Province

A Novel Stability Indicating HPLC Assay Method for Simultaneous Estimation of Clopidogrel and Aspirin in Tablet dosage form by Using Core shell Technology column

A novel, rapid and a stability-indicating reverse phase LC method has been developed and validated for the simultaneous estimation of Clopidogrel and Aspirin in tablet dosage form. The chromatographic separation was achieved on a novel core shell technology phenyl hexyl stationary phase of particle size 2.6μ. The method employed a linear gradient elution and the detection wavelength was set at 220nm. The proposed method was extensively validated as per ICH guidelines. The specificity of the method was proved by performing forced degradation studies. Regression analysis shows r value (correlation coefficient) of greater than 0.999 for individual active drug substances. Accuracy was proved in the range of 50% to 150% of working range.

О механизме прогрессирующего обрушения высотного здания втц-7 во время событий 11 сентября 2001 года в Нью-Йорке

The collapse of 47-storeyed WTC-7 skyscraper which occurred during 7 hours after terrorist attacks on the Twin Towers of the World Trade Center became the main riddle of the events of September 11,2001. The WTC-7 skyscraper wasn't a direct object of terrorist attack therefore circumstances of progressing collapse of this building caused fair amount of serious research, and also was followed by numerous myths and falsifications of events of September 11, 2001. The version of the mechanism of WTC-7 progressing collapse, presented in this article, is based on the theory of fire resistance of objects in case of exposure to combined hazardous effects (CHE) taking into account the crucial role of creep strain of steel constructions under such conditions. It is noted that propagation of creep strain of the steel constructions under described conditions was so considerable that could cause partial damage of their fire protection and eventually lead to the fire resistance exhaustion and to buckling of the steel columns in east part of the stiffening core during a fire. As a result of loss of the bearing capacity of stiffening core columns, due to the redistribution of load on the external envelope of the building, the critical warm-up temperature of external envelope columns (in a fire development zone) decreased to the level of their warm-up temperatures during a fire. It led to loss of bearing capacity of the external envelope columns in a fire zone and to total destruction of WTC-7.

On-line SPE–UHPLC method using fused core columns for extraction and separation of nine illegal dyes in chilli-containing spices

The presented work describes the development of a simple, fast and effective on-line SPE–UHPLC–UV/vis method using fused core particle columns for extraction, separation and quantitative analysis of the nine illegal dyes, most frequently found in chilli-containing spices. The red dyes Sudan I–IV, Sudan Red 7B, Sudan Red G, Sudan Orange G, Para Red, and Methyl Red were separated and analyzed in less than 9min without labor-consuming pretreatment procedure. The chromatographic separation was performed on Ascentis Express RP-Amide column with gradient elution using mixture of acetonitrile and water, as a mobile phase at a flow rate of 1.0mLmin−1 and 55°C of temperature. As SPE sorbent for cleanup and pre-concentration of illegal dyes short guard fused core column Ascentis Express F5 was used. The applicability of proposed method was proven for three different chilli-containing commercial samples. Recoveries for all compounds were between 90% and 108% and relative standard deviation ranged from 1% to 4% for within- and from 2% to 6% for between-day. Limits of detection showed lower values than required by European Union regulations and were in the range of 3.3–10.3µgL−1 for standard solutions, 5.6–235.6µgkg−1 for chilli-containing spices.