Rolling Procedure Research Articles

Forecasting Daily Room Rates on the Basis of an LSTM Model in Difficult Times of Hong Kong: Evidence from Online Distribution Channels on the Hotel Industry

Given the influence of the financial-economic crisis, hotel room demand in Hong Kong has experienced a significant drop since June 2019. Given that studies on the room rate aspect remains limited, this study considers the demand for hotel rooms from different categories and districts. This study makes forecast attempts for room rates from mid-October of 2019 to mid-June of 2020, which was a difficult period for Hong Kong owing to the onset of the social unrest and novel coronavirus outbreak. This study develops an approach to the short-term forecasting of hotel daily room rates on the basis of the Long Short-Term Memory (LSTM) model by leveraging the key properties of day-of-week to improve accuracy. This study collects a data set containing 235 hotels of the period from various online distribution channels and generates different time series data with the same day-of-week. This study verifies the proposed model through three baseline models, namely, autoregressive integrated moving average (ARIMA), support vector regression (SVR), and Naïve models. Findings shed light on how to lessen the impact of violent fluctuations by combining a rolling procedure with separate day-of-week time series for the hospitality industry. Hence, theoretical and managerial areas for hotel room demand forecasting are enriched on the basis of adjusting room pricing strategies for hoteliers in improving revenue management and making appropriate deals for customers in booking hotel rooms.

Evolution of microstructure and texture in the third generation Al–Li alloy AA2195 during warm hybrid processing

In the present study, the evolution of microstructure, crystallographic texture and their influence on mechanical properties of the Al–Li alloy, AA2195 has been studied. A novel hybrid processing route involving warm multi-axial forging (MAF) and subsequent warm rolling was employed. Different rolling procedures were followed to obtain optimal microstructure and properties. The processing conditions significantly influenced the course of evolution of microstructure and texture. A variation in tensile properties as a function of angle from RD for the differently processed samples was noticed. The tensile properties were closer to isotropic case for the samples deformed using a combination of MAF with cross rolling. By controlling grain size and texture through optimal processing, it was possible to achieve isotropic tensile properties in the AA2195 alloy. The processing conditions have also led to enhancement in strength, which has been attributed to grain boundary strengthening, precipitation strengthening and dislocation strengthening.

Effects of cross rolling on texture, mechanical properties and anisotropy of pure Mo plates

Abstract To clarify the influence of the deformation texture on the mechanical properties, pure Mo plates were processed by various cross rolling procedures, and the relation among texture, microstructure and mechanical properties was discussed. The results show that cross rolling of the Mo plates is beneficial for the formation of the rotated cube component, i.e., {001}〈110〉. The corresponding orientation density exhibits a positive correlation with the total rolling deformation and the current-pass deformation. When the total deformation is 96% or greater, the Mo plates form a texture orientation dominated by {001}〈110〉, whereas the γ-fibre texture becomes weaker and the cube texture {100}〈100〉 disappears completely. The presence of {001}〈110〉 has great effects on the properties of cross-rolled Mo plates, which is beneficial for strength enhancement and plasticity reduction in both the rolling direction (RD) and the transverse direction (TD).

Mitigation of uncommon peel-off defects in galvanized steel sheets

Galvanizing defects occurring in hot-and cold-rolling procedures were studied by scanning electron microscopy and focused ion beam, and analyzed via the JMP software. The results show that, among the 200 bright spots dispersed along the hot dipping steel plate, the defect may be misidentified as zinc slag by the representation of coating surface, but there exists a tiny peel off on the matrix without oxide particles under each spot. Upon partial removal of zinc coating, a tiny iron film outcropped from the coating was revealed. As some of iron films are not adhered to the matrix, such outcrops are not detected. The cross-sectional morphology shows the formation of inhibition layer, with no oxide between the peel off and matrix. The relative cold and hot rolling plates are also analyzed to trace the source, that the defect is inherited from hot rolling process according to the results. By using JMP to calculate the relationship of hot rolling parameters with the defect, slab heating temperature is concluded as a strong correlation condition. The high slab heating temperature ensures smooth rolling procedure, but the intergranular binding force is too low, which enhances the coating surface separation from the matrix. After reducing the slab heating temperature from 1350 to 1300°C or lower, and optimization of descale and pickling parameters, the occurrence ratio of bright spot defects caused by peel-off was significantly reduced.

Strengthening a dual-phase Mg–Li alloy by strain-induced phase transformation at room temperature

Strain-induced phase transformation in a dual-phase Mg–Li alloy after a severe deformation has been investigated. β-Li phase was transformed into α-Mg phase as a consequence of large strain cold rolling. The morphology and density of the strain-induced phase could be controlled by slip activation in the β-Li phase. A multi-direction rolling procedure was designed to enhance phase transformation behavior. High density strain-induced phase refined phase structure and greatly promoted the yield strength of the material without a sacrificing the ductility. Strain-induced phase transformation is a potential method for improving the mechanical properties in dual-phase alloys.

Predictive and Prescriptive Analytics toward Passenger-centric Ground Delay Programs

Ground Delay Programs (GDP) comprise the main interventions to optimize flight operations in congested air traffic networks. The core GDP objective is to minimize flight delays, but this may result in optimal outcomes for passengers — especially with connecting itineraries. This paper proposes an original passenger-centric approach to GDP by leveraging data on passenger itineraries in flight networks. First, we identify analytical drivers of passenger-centric operations in transportation systems. Second, we develop an integer program that balances flight delays and passenger delays in large-scale GDP operations. A rolling procedure decomposes the problem while ensuring global feasibility, enabling the model’s implementation in short computational times. Third, we propose statistical learning models to predict passenger itineraries and optimize GDP operations accordingly, enabling the model’s implementation when passenger itineraries are unknown by air traffic managers. Computational results based on real-world data suggest that our modeling and computational framework can reduce passenger delays significantly at small increases in flight delay costs, and that these benefits are robust to imperfect knowledge of passenger itineraries. Results highlight two major levers of passenger-centric operations: (i) delay allocation (which flights to delay vs. prioritize), and (ii) delay introduction (whether to deliberately hold flights to avoid passenger misconnections).

Novel α + β Type Ti-Fe-Cu Alloys Containing Sn with Pertinent Mechanical Properties

Rising demand for bone implants has led to the focus on future alternatives of alloys with better biocompatibility and mechanical strength. Thus, this research is dedicated to the synthesis and investigation of new compositions for low-alloyed Ti-based compounds, which conjoin relatively acceptable mechanical properties and low elastic moduli. In this regard, the structural and mechanical properties of α + β Ti-Fe-Cu-Sn alloys are described in the present paper. The alloys were fabricated by arc-melting and tilt-casting techniques which followed subsequent thermo-mechanical treatment aided by dual-axial forging and rolling procedures. The effect of the concentrations of the alloying elements, and other parameters, such as regimes of rolling and dual-axial forging operation, on the microstructure and mechanical properties were thoroughly investigated. The Ti94Fe1Cu1Sn4 alloy with the most promising mechanical properties was subjected to thermo-mechanical treatment. After a single rolling procedure at 750 °C, the alloy exhibited tensile strength and tensile plasticity of 1300 MPa and 6%, respectively, with an elastic modulus of 70 GPa. Such good tensile mechanical properties are explained by the optimal volume fraction balance between α and β phases and the texture alignment obtained, providing superior alternatives in comparison to pure α- titanium alloys.

Strengthening a Dual-Phase Mg-Li Alloy by Strain-Induced Phase Transformation at Room Temperature

Strain-induced phase transformation in a dual-phase Mg-Li alloy after a severely deformation has been characterized. β-Li phase was transformed into α-Mg phase during large strain cold rolling. The morphology and density of strain-induced phased could be controlled by slip activation in the β-Li phase. A multi-direction rolling procedure was designed to enhance phase transformation behavior. High density strain-induced phase refined phase structure and greatly promoted the yield strength of the material without a decrease in ductility. Strain-induced phase transformation was a potential method for the improvement of mechanical properties in dual-phase alloys.

Fabrication and scale-up of multi-leaf spiral-wound membrane modules for CO2 capture from flue gas

Facilitated transport membranes for CO2 capture from flue gas were scaled up and subsequently fabricated into spiral-wound modules. In order to increase the membrane area in each module conveniently, a multi-leaf rolling procedure utilizing a carrier layer was used, and the fabrication steps were documented in detail. The prototype module comprised up to 7 membrane leaves (each membrane leaf had dimensions of 14″ by 36″) and had a total membrane area of up to 2.94 m2. By controlling the spacer thicknesses, the packing density in each of the modules was enhanced, while the pressure drops on both feed and permeate sides were maintained below 1.5 psi/m. The fabricated membrane modules showed consistent transport results as the corresponding scale-up membranes. For instance, a CO2 permeance of 1450 GPU and a CO2/N2 selectivity of 185 were achieved with a simulated flue gas at 67 °C. Furthermore, the pressure drop and concentration polarization phenomenon were quantitatively correlated to the feed flow rate. The developed correlations were used to predict the separation performance of a full-size (8″ × 40″) module.

An investigation into the development of right displaced abomasum by rolling 268 dairy cows with left displaced abomasum

Right displaced abomasum (RDA) and abomasal volvulus (AV) are common diseases in cattle. However, presently there is no consensus regarding the pathogenesis and nomenclature of the different positions that the abomasum can adopt in the right side of the cow. Therefore, the objective of this study was to describe the etiopathogenesis of the right displaced abomasum according to the description of the features observed in 268 cows with left displaced abomasum (LDA), which were rolled to induce the movement of the abomasum from the left side to the right (in fact, inducing an RDA in 44% of cases), to facilitate the surgical approach, and immediately surgically treated (abomasal omentopexy from the right side). The observed RDA positions matched previously published descriptions and names, and the authors propose a holistic and simpler nomenclature and a clear hypothesis on RDA etiopathogenesis. In 54.1% of the cases, the abomasum moved to a normal position after rolling. The most common RDA position observed was caudal displacement of the RDA (CdRDA; 70 out of 119 RDA cases; 26.1% of the total number of cows), followed by lateral displacement (LRDA; 32 of 119; 11.9% of all cases), cranial displacement (CrRDA; 8 of 119; 3% of the total), medial displacement (MRDA; 4 of 119; 1.5% of the total), and finally, displacement lateral to the omasum (LORDA; 3 of 119; 1.1% of the total). Adverse events directly due to the rolling procedure were mesenteric root volvulus (3 of 268), cecocolic volvulus (2 of 268) and torsion (1 of 268), and uterus torsion (2 of 10 pregnant cows); 1 abortion (1 of 10 pregnant cows) was also observed. We suggest that CdRDA is the first stage of an RDA that can become an LRDA with increasing pressure. An LRDA can become an AV if rotating counterclockwise, viewed from above. An LDA, CdRDA, or LRDA could be initial forms of LORDA and CrRDA, and occur when forestomachs are empty or when the animal stands up on its front legs first. The LORDA and CrRDA forms can lead to an omasum-abomasum volvulus (OAV) or to a reticulum-omasum-abomasum volvulus (ROAV) when pressure increases. With this study we establish, for the first time, the sequence and incidence of each RDA form and its complications, increasing knowledge of this syndrome and its pathogenesis. This understanding critically aids the surgeon's ability to accurately assess and correct this disease and to predict prognosis.

Slip behavior and its effect on rolling texture development in a dual-phase Mg–Li alloy

Microstructure and texture evolution of Mg-8.8 wt%Li-0.8 wt%Zn dual-phase alloy during cold rolling to 70% thickness reduction were investigated. The results showed that both α-fiber and γ-fiber of β-Li phase were enhanced during the cold rolling procedure and {001}<110> was the dominant texture component. A double-peak texture with a large tilt angle of 28° was observed in α-Mg phase. Each peak of this texture component exhibited a wider orientation spread towards the transverse direction. This spread is related to the strong activation of pyramidal II slip. Basal slip was still the dominant slip mode and the activities of pyramidal I and pyramidal II slip were also largely enhanced. Schmid factor analysis and viscoplasitc self-consistent simulation jointly suggests that the development of the rolling texture in α-Mg phase can be ascribed to the competition between basal slip and pyramidal slip.

The Influence of Warm Rolling on Microstructure and Deformation Behavior of High Manganese Steels

In this work, a Fe23Mn0.3C1Al high manganese twinning-induced plasticity (TWIP) steel is subjected to varying warm rolling procedures in order to increase the yield strength and maintain a notable ductility. A comprehensive material characterization allows for the understanding of the activated deformation mechanisms and their impact on the resulting microstructure, texture, and mechanical properties. The results show a significant enhancement of the yield strength compared to a fully recrystallized Fe23Mn0.3C1Al steel. This behavior is mainly dominated by the change of the active deformation mechanisms during rolling. Deformation twinning is very pronounced at lower temperatures, whereas this mechanism is suppressed at 500 °C and a thickness reduction of up to 50%. The mechanical properties can be tailored by adjusting rolling temperature and thickness reduction to desired applications.

Management Controlling of Progamme Desa Mandiri Cinta Petani in Timor Tengah Utara Regency

Management controlling is a important role in the implementation of a program, because this function has a role to measure the suitability of activities with a predetermined plan. The purpose of this study was to analyze and describe the supervisory function in the management of the independent love village farmers program (Sari Tani) in Timor Tengah Utara Regency. The formulation of the problem in this study is how the supervision function of the farmer sari program in Timor Tengah Utara Regency. To answer these problems, the management is used which has relevance to the phenomenon of research. This research is a qualitative research with Milles and Huberman data analysis techniques. The results of the study showed that control in the program management of the independent love villages of farmers in Timor Tengah Utara Regency was not yet in line with the technical guidelines. As a result of the large amount of arrears on farmer sari refunds and the jamming of the farmers' funds, due to lack of awareness of beneficiaries who do not want to return Fund of sari tani programs (DST), Sari Tani Programe management unit (UPST) administrators do not comply with regulations relating to DST rolling procedures, and there is no direct action or direct affirmation to beneficiaries who have not repaid the refund of the farmer's juice.

Research on rolling bearing fault diagnosis based on multi-dimensional feature extraction and evidence fusion theory.

Rolling bearing failure is the main cause of failure of rotating machinery, and leads to huge economic losses. The demand of the technique on rolling bearing fault diagnosis in industrial applications is increasing. With the development of artificial intelligence, the procedure of rolling bearing fault diagnosis is more and more treated as a procedure of pattern recognition, and its effectiveness and reliability mainly depend on the selection of dominant characteristic vector of the fault features. In this paper, a novel diagnostic framework for rolling bearing faults based on multi-dimensional feature extraction and evidence fusion theory is proposed to fulfil the requirements for effective assessment of different fault types and severities with real-time computational performance. Firstly, a multi-dimensional feature extraction strategy on the basis of entropy characteristics, Holder coefficient characteristics and improved generalized box-counting dimension characteristics is executed for extracting health status feature vectors from vibration signals. And, secondly, a grey relation algorithm is used to calculate the basic belief assignments (BBAs) using the extracted feature vectors, and lastly, the BBAs are fused through the Yager algorithm for achieving bearing fault pattern recognition. The related experimental study has illustrated the proposed method can effectively and efficiently recognize various fault types and severities in comparison with the existing intelligent diagnostic methods based on a small number of training samples with good real-time performance, and may be used for online assessment.

Rational Design of Robust Si/C Microspheres for High-Tap-Density Anode Materials.

Si has been recognized as a next-generation anode alternative to graphite for high-energy-density lithium-ion batteries. However, the most intractable problem of previous Si-based anodes is the relatively low compressive strength of particles because of excess voids and porous structures, thus leading to poor structural integrity and electrochemical performance under high pressure of the rolling procedure in practical application. Therefore, a rational design of robust Si/C microspheres with a compact nano/microstructure is an effective strategy to address the above-mentioned issues. In this ingenious structure, Si nanoparticles are homogeneously dispersed and anchored on flake graphite and then the composites self-assemble into microspheres via polycondensation and surface tension of pitch under high temperature and high pressure. Benefitting from this innovative approach and rational design, the obtained robust Si/C microspheres not only present high compressive property and high tap density (1.0 g cm-3) but also demonstrate high initial Coulombic efficiency (90.5%) and cycling stability with areal capacity (4 mA h cm-2) under a compaction density of 1.3 g cm-3. Furthermore, the full cell assembled with LiNi0.8Co0.1Mn0.1O2 and the resultant Si/C microsphere anode also displays good cycling performance and rate capabilities. Owing to these aspects, the proposed rational design of encapsulating Si nanoparticles in high-tap-density microspheres could be extended to load other nanomaterials for advanced batteries.

Effect of UDC Casting on Hot Deformation Behavior and Properties of 2A14 Aluminum Alloy

Uniform direct chill (UDC) casting is coupled annular electromagnetic stirring and intercooling, having been utilized for the preparation of large-sized aluminum alloy billet. In this paper, the UDC casting was applied to 2A14 aluminum alloy billets with a diameter of 584 mm. Hot compression tests, cogging and ring rolling procedures were carried out for the billets, respectively. The results show that during the deformation temperature of 420 °C and the strain rate of 0.01 s−1 to 10 s−1, the flow stresses of different positions are higher and more stable in the UDC casting billet than in the normal direct chill (NDC) casting billet. The dislocation glide is the dominant deformation mechanism of 2A14 aluminum alloy. Meanwhile, the UDC casting significantly improves the mechanical properties of the rolled rings in tangential and axial directions compared with the NDC casting.

Investigation of the Process of Screw Rolling in a Four-Roll Stand by Simulation

We designed and produced a working model of new four-roll mill with the use of additive technologies. The model has two driven working rolls and two driven auxiliary rolls for screw rolling of round billets. Plasticine billets were rolled in the model mill to show that the four-roll screw rolling is possible. The experimental rolling was simulated by using the QForm software. The accuracy of computer simulations was estimated by comparing the dimensions of the billets obtained after rolling and as a result of computer simulations. We simulated the procedure of rolling of a round billet of alloyed steel both in a four-roll mill and in a three-roll mill with radial-shear rolling. According to the results of computer simulations, it was shown that the variations of the diameter along the length of the billet and the total work required to realize shape-forming are lower for the four-roll mill.

Microstructure and Fabrication of Cu-Pb-Sn/Q235 Laminated Composite by Semi-Solid Rolling

In the present work, Cu-Pb-Sn and Q235 laminated composite were fabricated by a horizontal semisolid rolling procedure. The interfacial structure, elemental distribution, and properties of the composite were investigated. Finite-element simulation was conducted to analyze the temperature field and solidification process during the semisolid rolling. An appropriate semi-solid region was observed at a pouring temperature of 1598 K in the simulation, which would effectively kept fluidity and avoided casting defects. The experimental results showed that good interface between Cu-Pb-Sn alloy and Q235 steel was achieved by the proposed process at 1598 K, without casting defects or excessive deformation. The Cu and Fe alloys were bonded mainly by the diffusion of Fe into Cu matrix, and a handful of microscopic Pb-rich layer. Fine Pb-rich precipitates were uniformly distributed in the Cu-Pb-Sn alloy, and were considered to be advantageous to the self-lubrication property. The average tensile-shear strength of the interface was higher than 57.68 MPa at a pouring temperature of 1598 K, which fulfilled the requirements for a further extrusion process.

A novel rolling procedure to enhance ECAP processed ultrafine grained materials

The present study proposes a novel approach to rolling in order to achieve further microstructure modification and mechanical properties improvement of already severely deformed materials. Commercially pure aluminium was subjected to the combined, two stages, heavy strain processes. First, samples were deformed using multi-turn equal channel angular pressing. Five passes of two-turn channel resulted in high strain level, which equaled 11.5. After such a deformation, the microstructure consists of ultrafine grained structure with the fraction of high angle grain boundaries equaled 61%. Then, the second plastic forming process was applied i.e. multi rotational flat rolling. Proposed multipass rolling is based on maintaining a square cross-section of the workpiece. Rolling of severely deformed sample with the thickness reduction of 25% resulted in the improvement in mechanical strength about 15%. It is caused by the increased fraction of high angle grain boundaries up to 75%, while differences in average grain/subgrain size between samples are insignificant.

A Passenger-Centric Approach to Air Traffic Flow Management

Traffic flow management initiatives aim to balance the flows of vehicles in capacity-constrained transportation networks to minimize congestion costs. While existing research has focused on vehicle-centric delay minimization objectives, this may not result in most efficient outcomes from the end users' perspective when travel itineraries involve connections between multiple vehicles. This paper develops an original user-centric approach to traffic flow management. First, an analytical Markov Decision Process is presented to derive structural insights on the drivers of user-centric operations. Second, this paper augments existing air traffic flow management (ATFM) models by explicitly balancing flight delay costs and passenger delays. A large-scale integer programming model is formulated to track the impact of flow management operations on passenger accommodations. An original rolling procedure decomposes the problem over time while ensuring global feasibility, and shown to enable the model's implementation in short computational times. Computational results in the US National Aviation System suggest that this modeling and computational framework can achieve large reductions in passenger delays at comparatively small increases in flight delay costs. Analytical and computational results highlight two major levers of user-centric operations: (i) delay allocation, which determines which flights to delay or prioritize to minimize delay costs, and (ii) delay introduction, which deliberate adds departure holds to avoid passenger misconnections.