•A novel tube insert (bidirectional conical strip inserts) is proposed for heat transfer enhancement.•Multiple longitudinal swirl flow structure is formed in tube with the inserts.•Effects of ...geometric parameters are examined numerically.•Correlation formulas for Nusselt number and friction factor are derived.
In the present work, a novel tube insert (bidirectional conical strip inserts) is proposed, and the heat transfer performance and flow characteristics of this insert are studied numerically. Effects of three geometric parameters (numbers of bidirectional conical strip (n), central angle (α) and pitch ratio (P∗ = p/D)) are also investigated. The results indicate that cold fluid in the core region and the hot fluid near the tube wall are rapidly exchanged as the fluid flows through the bidirectional conical strip, and multiple longitudinal swirling flows are formed downstream of the bidirectional conical strip. Therefore, the heat transfer (the Nusselt number) is significantly enhanced by 2.35–9.85 times compared to the smooth tube. Moreover, because of the cooperation between the forward and the reverse conical strips, the formation of the dead zone and eddy on the back of the conical strips is inhibited. Thus, the increase in flow resistance is smaller than many other published works, as the friction factor is enhanced to 2.37–21.18 times of the smooth tube. The overall heat transfer performance (PEC value) is located in range of 1.75–3.93. Both the Nusselt number and friction factor increase with the increasing numbers of bidirectional conical strip, central angle and the decreasing pitch ratio. However, the friction factor is more sensitive to geometric parameters, so the maximum overall heat transfer performance (PEC value) is obtained at moderate geometric parameters (n = 3, α = 40° and P* = 3). In addition, Correlation formulas for Nusselt number and friction factor are derived.
The surface defects of a hot-rolled strip will adversely affect the appearance and quality of industrial products. Therefore, the timely identification of hot-rolled strip surface defects is of great ...significance. In order to improve the efficiency and accuracy of surface defect detection, a lightweight network based on coordinate attention and self-interaction (CASI-Net), which integrates channel domain, spatial information, and a self-interaction module, is proposed to automatically identify six kinds of hot-rolled steel strip surface defects. In this paper, we use coordinate attention to embed location information into channel attention, which enables the CASI-Net to locate the region of defects more accurately, thus contributing to better recognition and classification. In addition, features are converted into aggregation features from the horizontal and vertical direction attention. Furthermore, a self-interaction module is proposed to interactively fuse the extracted feature information to improve the classification accuracy. The experimental results show that CASI-Net can achieve accurate defect classification with reduced parameters and computation.
The Silicon Vertex Detector of the Belle II experiment Uematsu, Y.; Adamczyk, K.; Aggarwal, L. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
06/2022, Letnik:
1033
Journal Article
Recenzirano
Odprti dostop
The Silicon Vertex Detector (SVD) is a part of the vertex detector in the Belle II experiment at the SuperKEKB collider (KEK, Japan). Since the start of data taking in spring 2019, the SVD has been ...operating stably and reliably with a high signal-to-noise ratio and hit efficiency, achieving good spatial resolution and high track reconstruction efficiency. The hit occupancy, which mostly comes from the beam-related background, is currently about 0.5% in the innermost layer, causing no impact on the SVD performance. In anticipation of the operation at higher luminosity in the following years, two strategies to sustain the tracking performance in future high beam background conditions have been developed and tested on data. One is to reduce the number of signal waveform samples to decrease dead time, data size, and occupancy. The other is to utilize the good hit-time resolution to reject the beam background hits. We also measured the radiation effects on the full depletion voltage, sensor current, and strip noise caused during the first two and a half years of operation. The results show no detrimental effect on the SVD performance.
Heat transfer enhancement is the process of increasing the heat-transfer coefficient, which enhances the system's performance. Enhancing heat transfer is a major problem for saving energy and is also ...beneficial economically. Many passive devices are used inside tubes to improve heat transfer such as twisted tape inserts, rough parts, extended surfaces, additives for liquids wire plugs, etc. This research reviewed one of the most effective passive devices which are twisted tape inserts. Since it has many advantages such as simple fabrication, simple operation, and ease of maintenance. The twisted tape inserts generated swirl flow and vortex inside the tube. Therefore, the internal convective heat transfer process is significantly improved. The current research article provides an overview of different twisting tape inserts that can improve heat transfer rates. By reducing boundary layer thickness near tube walls. Which lead to reduce the size and cost of many industrial applications, including heat exchangers, refrigeration systems, air conditioners, reactors, thermal power plants, spacecraft, and automobiles. A summary of previous experimental and numerical studies is presented as well. The primary results indicated that the twisted tape inserts are demonstrated to be efficient in enhancing heat transfer inside the tube for laminar and turbulent flow. But during a turbulent flow, twisted tapes increased pressure loss more than laminar flow because of flow obstruction.
Aflatoxin M1 (AFM1), a frequently occurring mycotoxin in milk and dairy products, causes acute and chronic poisoning. In this study, we developed a time-resolved fluorescence microsphere ...immunochromatographic test strip (TRFM–ICTS) combined with ultraviolet light for the rapid and quantitative detection of AFM1 in milk and its products. Polystyrene microspheres enclosing time-resolved fluorescent europium (III) Eu(III)-TRFM were prepared as a label and then conjugated to a monoclonal antibody. Pre-incubation was introduced for competitive recognition. Under optimal conditions, TRFM–ICTS had a linear range of 0.05–2.0 ng/mL with a 50% inhibitory concentration (IC50) of 0.204 ng/mL, which was nearly five–fold lower than those of ICTS in a traditional structure with traditional pretreatment (IC50 = 1.10 ng/mL). This test strip enhanced the sensitivity from 0.3 ng/mL (by using gold nanoparticles-strip method previously reported) to 0.019 ng/mL (by using this TRFM–ICTS method). The improved sensitivity may be due to the detection signals of immunoassay probes (with each fluorescence microsphere coupled with numbers of antibodies). TRFM–ICTS exhibited good recoveries ranging from 84.6% to 119.0% with a coefficient of variation (CV) lower than 8.31% in spiked samples, including milk powder, ultrahigh-temperature (UHT) and pasteurized milk. The results obtained using TRFM–ICTS were consistent with those obtained by ultrahigh–performance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS) during testing of real milk samples. In addition, TRFM–ICTS has a longer storage period, which basically meets the needs of the commercial market. Owing to its high sensitivity and practicability, the proposed TRFM–ICTS can be used as a sensitive, simple, rapid, and versatile method for the quantitative detection of AFM1 in milk.
•Developing a time-resolved fluorescent immunochromatographic assay for aflatoxin M1.•Pre-incubation was introduced for competitive recognition.•The sensitive and stable assay was used for AFM1 detection in milk.•The assay could quantitatively detect AFM1 by consuming less monoclonal antibody.•An immunostrip with a detection limit of 0.019 ng/mL for AFM1 was developed.
•Upward two-phase flow in confined geometries such as offset-strip fins.•Influence of operating conditions on upward two-phase flow.•Influence of the use of binary mixtures on heat and mass transfer ...modes.•Introduction of new correlations for pressure drops and heat transfer coefficients for binary zeotropic mixtures in offset strip fins.
The current study focuses on an experimental investigation of upward vertical two-phase flow of binary mixtures in complex geometries composed of offset-strip fins. The flow boiling of a mixture containing 52% mol/mol of R-134a and 48% mol/mol of R-245fa was visualized. The ranges of mass flux and heat flux investigated were 11 – 25 kg.m−2.s−1 and 9 – 23 kW.m−2 respectively. The test section is an offset-strip finned passage whose hydraulic diameter is 1.75 mm. The operating pressure ranges from 2 to 5 bar absolute. The temperature glide of the used binary mixture ranges from 14 to 16 °C. Different flow regimes were identified along the test section such as bubbly, slug and annular regimes. The impact of strip-fins and mass flux on flow maps was analysed in this study. The pressure drop was analyzed and the obtained data were gathered to propose a new correlation for R-134a/R-245fa mixture in offset-strip fins. The local heat transfer coefficient was calculated and it has been found that nucleate boiling was the predominant mode of heat transfer.
•Plant shoot architecture affected the sediment trapping potential of VFS.•Tillering of Lolium perenne with growth led to drastic increase in sediment trapping.•Plant dynamics can be handled ...effectively by VFSMOD.•Silty-clay sediment trapping capacity upstream to the VFS was limited.
Vegetative filter strips (VFS) implemented downstream to the source of pollution can trap sediments and thus limit sediment export from agricultural fields. However, their retention efficiencies are determined by many factors, among others the type of plant species and its growth stage. The impact of plant growth and morphology, as well as of incoming sediment concentration, on the efficiency of VFS to trap sediments was assessed by means of an experimental flume. Two different plant species were tested, Lolium perenne and Trifolium repens, after 2 and 4months of plant growth and for 2 different incoming silty-loam sediment concentrations. Measured retention efficiencies were compared to simulated values using VFSMOD based on goodness-of-fit indicators that take into account uncertainty linked to the measurements.
The sediment storage capacity upstream of the VFS was limited in terms of mass, and therefore an increase in sediment concentration led to a decrease in sediment retention efficiency. After 2months of plant growth, plant morphology affected the VFS potential to trap sediments, as reflected in the higher retention efficiency of T. repens due to its creeping shoot architecture. However, plant growth and development modified the plant morphology and VFS trapping potential. Indeed, L. perenne VFS retention efficiency increased from 35% after 2months of growth to 50% after 4months, due to the tillering capacity of grass species. Conversely, the trapping efficiency of T. repens decreased from 49% to 40% after 4months. This highlights the possible degradation of VFS with time, which in the case of T.repens was due to an increased heterogeneity of plant density within the strips. These modifications of plant characteristics with growth stage, which affected sediment trapping efficiencies, can be effectively integrated into mechanistic models like VFSMOD, mainly through stem spacing and Manning’s surface roughness coefficient inputs. Since these parameters were highly conditioned by plant growth and development, modelers should take into account plant dynamics and select plant parameters related to the actual field conditions.
The widespread use of reinforced-soil walls, especially in seismic regions has led to extensive studies on seismic behavior of this structures. In this paper, to assess the behavior and performance ...of steel-strip reinforced-soil retaining walls during seismic loading, a series of 1-g shaking table tests were conducted on 0.9m high reinforced-soil wall models with different strip lengths. The physical models were subjected to variable-amplitude harmonic excitation at different peak accelerations and durations. It was found that the deformation mode of walls highly depends on the length of strips. The observed predominant mode of deformation was combination of bulging of the facing and rotation about the wall base without base sliding. The pattern of the observed failure mechanisms included a moving block which is delineated by a combination of a slant and reverse curve with certain intersection point. Irrespective of different steel strip lengths, the threshold acceleration corresponding to the onset of plastic displacements was similar and equal to 0.5g for all models and the threshold acceleration corresponding to the onset of the development of active wedge failure was dependent on strip length so that this critical acceleration increased with increasing the strip length. Also, a consistent range of ∆x/H' between 0.2% and 0.8% (or ∆x/H'=0.2–0.8%) representing a transitional state of the walls from quasi-elastic to plastic state and a consistent range of ∆x/H' between 4.5% and 4.9% (or ∆x/H'=4.5–4.9%) representing a transitional state of the walls from plastic to failure state were observed. On the other hand, according to the sudden increase in wall displacements caused by decreasing the strip length from 0.7H' to 0.5H', the L/H' ratio of 0.7 was presented as the critical ratio in seismic conditions.
•The seismic behavior of steel-strip reinforced-soil retaining wall was investigated.•Strip length, peak acceleration and loading duration were defined as research variables.•The pattern of failure mechanisms was defined as a function of strip length.•Irrespective of strip length, the boundaries of performance levels were defined.•L/H'= 0.7 was presented as the critical ratio in seismic conditions.
A simple, flexible, disposable and low cost non-enzymatic electrochemical biosensor for the selective and sensitive detection of environmentally hazardous pesticide namely methyl parathion (MP) is ...demonstrated using chemically modified overhead projector sheets employed as disposable strips.
•Chemically modified OHP strips as flexible and disposal sensor for MP detection.•Proposed electrochemical sensor exhibits higher sensitivity and lowest detection limit.•Methyl parathion sensing by monitoring its catalytic reduction process using DPV.•Non-enzymatic approach for pesticide detection using flexible and disposable strips.
A new, flexible and chemically modified disposable strip is demonstrated to be an efficient electrochemical sensor for the detection of environmentally hazardous pesticide, namely methyl parathion (MP). These disposable strips are prepared by surface modification of nonconductive polyester of polyvinyl alcohol sheets used as overhead projector (OHP) films with 3-mercaptopropyltrimethoxysilane (MPTMS) layers followed by electroless deposition of silver (Ag/MPTMS/OHP), essentially to bring in the conductivity and catalytic activity towards MP detection. Further deposition of zinc oxide (ZnO) onto Ag/MPTMS/OHP strips results in enhanced reduction current towards MP sensing. This is attributed to the ability of ZnO to promote electron transfer reaction and its large surface area arising out of the resultant nanostructured material during deposition leading to effective adsorption of MP molecules on such chemically modified strips. Structural and morphological characterizations of these strips are carried out by using field emission scanning electron microscope (FESEM) and X-ray diffraction (XRD) studies. Electroanalytical results show that these strips are selective and sensitive to MP detection over a wide linear concentration ranging from 2.5nM to 75μM along with a sensitivity value of 2.7632μA/μM. A very low detection limit of 0.07nM is determined for the proposed sensor. Moreover, this non-enzymatic electrochemical sensor is applied further to determine MP in real samples analysis and the results obtained are promising.
Agricultural intensification and the conversion of natural landscapes into annual cropping systems have contributed to declines in pollinator abundance and biodiversity. Increasing the abundance of ...flowering plants within crop fields is an often-overlooked practice that may be used to help sustain and enhance pollinator populations. In this study, the influence of red clover (Trifolium pratense) used as an interplanted living mulch on pollinator richness and visitation rates was evaluated and compared with monoculture sweet corn habitats. Treatments included sweet corn interplanted with red clover or monoculture with or without cover crop residue. Weekly visual observations of foraging floral visitors revealed that multiple species of bumblebees and butterflies, as well as honeybees frequently visited red clover flowers. Observations of visitors foraging on sweet corn tassels during pollen shed revealed distinct insect communities were attracted by sweet corn and red clover plants. Findings provided evidence that the inclusion of red clover in crop fields can increase the diversity and abundance of bees and butterflies on arable lands by serving as an important food source.
