Cut Size Research Articles

Weather shocks affect trade policy: Evidence from preferential trade agreements

AbstractWe show that weather shocks affect government trade policy decisions. We exploit variation in rainfall during the growing season within and across countries to show that weather shocks impact agricultural output and trade. Using information on tariff cuts by commodity from preferential trade agreements signed between 1995 and 2014, we then show that weather shocks that happen during the negotiation period correlate strongly with the size of tariff cuts. When weather shocks increase (decrease) a country's capacity to produce a given crop, its government negotiates a smaller (larger) tariff cut. These results are consistent with a political economy trade model with sector‐specific inputs in which the government places more weight on producers relative to consumers in its objective function. They also reveal that governments update their beliefs about domestic agricultural production capacity in response to weather shocks.

Establishment of particle motion model and study of particle volume fraction distribution in the turbo air classifier based on DSMC

In order to study the particles' motion law and collision behavior in the flow field of the turbo air classifier, A particle motion simulation platform is developed using Compute Unified Device Architecture (CUDA) based on the Visual Studio. The particle-eddy interaction model, the particle-wall collision model, and the inter-particle collision Direct Simulation Monte Carlo (DSMC) solver are implemented. The results show that the deviation between calculated cut size d50 and experimental d50 using DSMC is smallest compared to DSMC, DDPM and DPM. DSMC has better acceleration performance compared to DDPM. The more particles need to be calculated, the more significant this advantage is. The influences of feeding rate on particle volume fractions and inter-particle collision number are analyzed. The increase of feeding rate leads to the increase of the particle volume fractions and inter-particle collision number.

Collaborative design of atmospheric cutterhead opening and disc cutter arrangement

As the core components of the shield machine, the cutterhead body and the cutter directly interact with the soil, which plays a vital role in tunneling efficiency and performance. For the atmospheric cutterhead, the cutterhead opening and the cutter arrangement are mutually restricted, which brings great challenges to the design of the cutterhead. To solve this problem, an innovative collaborative strategy for cutterhead structure and cutter arrangement is proposed in this paper. By constructing a parametric model, we deeply analyzed the relationship between the cutterhead parameters and the cutter size and defined the feasible range of parameter changes. On this basis, we have developed a set of cutter arrangement specifications to ensure the coordinated operation between the cutter holders and between the cutter holder and the gate, avoiding potential interference problems, and calculating the minimum cutter spacing. In addition, the study also takes into account the various loads on the cutter and constructs a load model specifically for the atmospheric cutterhead. By taking an atmospheric cutterhead with a diameter of 15 m as an example, we elaborate on the implementation process of this method, which not only maximizes the cutterhead opening but also effectively controls the unbalanced load. The methodology of this study provides a new perspective and solution for the design of other types of cutterhead.

Canonical cuts of path powers

The MaxCut problem aims to find a bipartition of vertices in a given graph such that the number of edges with one end vertex in each part is maximum among all bipartitions. NP-hardness when restricted to interval graphs has been recently announced. Surprisingly, all previously published attempts at polynomial-time algorithms for unit interval graphs turned out to be wrong, which justifies the search for subclasses where MaxCut can be handled. We introduce canonical cuts whose pattern allows an easy computation of the cut size for the power of paths $P_n^k$. Using canonical cuts, we calculate the structure and the size of maximum cuts for $k\leq 5$ and for $n\leq \frac{2}{3}(2k+2)$. We prove that the known size for a maximum cut for reduced co-bipartite chain graphs can be achieved by a canonical cut. We perform computational experiments on each $P_n^k$ graph with $1\leq k\leq n\leq 43$ and show that most of them allow a canonical cut that is maximum. We display a table with the found cases where there is no canonical cut which is a maximum cut. In these graphs, the difference between the maximum cut and some canonical is at most 3 units. This indicates canonical cuts as a good approach to tackle the maximum cut on $P_n^k$ graphs.

Classification performance analysis of a louver classifier with a tilted sidewall and its application to the separation of unburned carbon from biomass combustion ash

Separating unburned carbon (UC) from biomass combustion ash is necessary to achieve high-quality ash as recyclable raw material and improve energy efficiency by reburning the UC in the furnace. In this study, a novel louver classifier geometry with tilted sidewall was proposed to separate the UC from biomass ash and its classification performance was analyzed via experiments and simulations. The louver classifier with a tilted sidewall provided a smaller 50% cut size and classification accuracy index indicating that the separation performance is improved. The CFD simulations revealed that tilted sidewall in the louver increased gas flow downward velocity in the classification region, increasing the inertia of the particles, and causing more particles to leave gas flow and deposit into the collection box as coarse ash. The UC of classified combustion ash increased with a decrease in the median mass diameter, indicating that the classification process for combustion ash produced coarse ash with a lower UC. The tilted sidewall in the modified louver classifier increased the reduction of unburned carbon (RUC) in ash up to 83.8%. The RUC increased with a cut size of the classified ash which was achieved when a high inlet flow velocity and high blow-up ratio are applied.

Experimental and simulation study of flow field characteristics of a disturbing rotary centrifugal air classifier

In the present study, a new disturbing rotary centrifugal classifier was designed and a method was proposed to characterize its pressure signals. The models for evaluating the classification effects were established based on multi-zones. It was found that the flow field, processing parameters, and material properties significantly affected on the particle force and classification performance. The pressure with high amplitude and energy analyzed using Hilbert-Huang Transform (HHT) concentrated within 200–400 Hz, and the screening cage facilitated energy transfer to lower frequency bands. Correlation analysis demonstrated the correlation coefficients (A5 and A6) between adjacent measurement points increased with frequency, further enhanced by the screening cage. The flow field of simulation was characterized by a low-pressure, high-velocity gradient at the center and a high-pressure, low-velocity gradient at the sidewalls and the gas velocity and flow for experiment achieved the maximum at z = 0.50 m, while the magnitude of pressure change was significant at the inlet end and discharge end, where the velocity gradient and pressure drop had the same trend and small errors for experiments and simulation. The flow field affected the competing relationship between centrifugal and drag forces on the particles with different kinematic behavior during the classification process. The errors between the predicted values of the theoretical, simulated, and experimental cut particle size models and the true values were all within 10 %, based on which the multi-zone classification efficiency model applicable to the disturbing centrifugal classifier was established, and it was found that the models all had high prediction accuracy and suitability. The article delves into the correlation between pressure signals, flow field characteristics and particle behavior, aiming to provide an important reference for the internal flow field and classification performance of air classifiers.

The influence of the guide vane positioning on the flow field of a turbo air classifier

AbstractAs the important component to guide the airflow in the classifier, installation position of the guide vane determines the width of the classification annular region and influences the flow field distribution. The influence of the guide vane positioning on the flow field in the annular region is analyzed through numerical simulation. The simulation results show the tangential velocities near the inner edge of the guide vanes increase, and the tangential velocity gradient decreases with decrease of the width of the annular region. The increases of turbulent dissipation rate near the guide vanes are beneficial to powder dispersion. However, the increases of turbulent dissipation rate near the rotor cage aren′t conducive to uniformity of the flow field. In case of the narrow annular region, the cut size gradually increases when the width of the annular region increases. However, when the width of the annular region continues to increase, the particle′s residence time become long, and the solid concentration increases significantly to increase the probability of particle aggregation. The reasonable range of the installation diameter of the guide vane in the classifier is between 504 mm and 524 mm.

Performance comparison of laboratory scale air classifier and hydrocyclone at the same target size

The research aimed at comparing the performances of two common centrifugal type classifiers, air classifier and hydrocyclone, operated dry and wet respectively. The reason for starting the study is the possible shifting to dry processing in the future as the water has limited availability. Such comprehensive research has not been undertaken in the literature although individual assessments were completed. Within the scope, copper ore, gold ore and magnetite-calcite blends were chosen as these applications are common globally. The research commenced with the experimental tests via laboratory scale air classifier and hydrocyclone. Afterwards, size analyses and component measurements (via XRF, MLA, fire assay) were undertaken. The data was initially used in mass balancing of the experimental data to adjust the flow rates alongside with assays then Tromp curves were plotted to determine cut size, sharpness of cut, bypass parameters. Comparison of the two classifiers were completed for the same overflow target sizes. Throughout the assessments, the magnitudes of the Tromp curve parameters for the overall classification and component-based results were compared. As a result, air classifier may be alternative to hydrocyclone classification since less bypass, higher sharpness values were obtained. This study provides insights on choosing the dry or wet classification.

Analysis of Cut Size Paper Cutting Machine Performance Using Total Productive Maintenance Concept (Case Study: PT. RST)

PT. RST, a leading paper factory in Indonesia, prioritizes timely production by optimizing productivity, efficiency, and paper quality. This study assesses the reliability of the Cut Size (CS) paper cutting machine, which is enhanced through the implementation of Total Productive Maintenance (TPM) as a management philosophy to ensure high-efficiency operations. To evaluate machine performance, Overall Equipment Effectiveness (OEE) measurement is used. From data collected from January to September 2023, an analysis is conducted to improve the performance of the CS machine, which has not met its set target. The average OEE value of 70.9% falls short of the target of 72%. This research aims to improve the performance of the CS machine through the TPM approach, focusing on the Focused Maintenance pillar. Using tools such as Pareto diagram, why-why analysis, fishbone diagram, and the 5W1H method, several sources of problems causing the decrease in OEE value will be identified and addressed.

An Empirical Study on the Upcycling of Glass Bottles into Hydrocyclone Separators

Cyclones are pivotal in mechanical process engineering and crucial in the complex field of separation technology. Their robustness and compact spatial requirements render them universally applicable and versatile across various industrial domains. Depending on the utilized fluid and field of application, both gas-based cyclones and hydrocyclones (HCs) are well established. Regarding HC design, enduring elongated flat cones have seen minimal alterations in shape and structure since their introduction over more than a hundred years ago. Experimental investigations regarding unconventional cone designs within scientific studies remain the exception. Therefore, this study focuses on alternative geometric configurations of the separation chambers and highlights their impact on separation and energy efficiency. To achieve this objective, different geometric shapes are investigated and retrofitted into HCs. The geometric foundation is derived from upcycled glass bottles. The repurposed bottles with a volume of 750 mL are used in conjunction with an inlet part, following the established Rietema design. Experimental tests are conducted with dilute phase separation, using 0.1–200 µm test particles in water. Comparisons between a bottle-based HC and a conventional Rietema design were conducted, establishing a benchmark against the standard. The findings revealed a noticeable correlation between separation efficiency and cone geometry. Conical designs demonstrated enhanced separation, particularly at lower volume flows. At the highest volume flow of 75 L min−1, the best performing bottle cyclones showed separation efficiencies of 78.5%, 78.4% and 77.9% and therefore are in a competitive range with 78.0% efficiency, achieved using the commercial Rietema design. Minimal disparities in cut sizes were observed in terms of separation grade efficiency among the models tested. Variations in separation efficiency and fractional efficiency curves indicated nuanced differences in classification efficiency.

Kirigami sheets in fluid flow

Kirigami patterned materials have found several applications in recent years due to their ability to assume complicated shapes and exhibit emergent physical properties when exposed to external forces. Consisting of an array of cuts in a thin material, fabrication of these patterns can be quite simple. Here we show that when they are placed in fluid flow, kirigami cut sheets with various patterns produce a variety of flow patterns in the wake. Through several sets of experiments, we show that kirigami sheets placed in flow can undergo static or dynamic flow-induced instabilities as a result of which they can buckle or undergo limit cycle oscillations, or they can remain stable while undergoing very large elongations. These structural responses produce several different types of fluid patterns in the wake. We show that vortices both at small scales (scales comparable with the size of the individual kirigami cuts) and large scale (scales comparable with the size of the sheet) are formed in the wake of kirigami sheets. We also show that jets of different sizes can be formed and directed passively using kirigami sheets. These results show the potential of kirigami sheets for passive flow control.

Parameter optimization of the classifying device of straw micro-crusher based on neural network and CFD

To improve the classification performance of the straw micro-crusher's classifying device, the characteristic parameters impacting classification performance are identified through an analysis of the forces acting on the straw particles between the blades of the rotor cage and the motion characteristics of the fluid. Taguchi's experimental design is used to ascertain the combinations of computational fluid dynamics (CFD) simulation parameters for cut size and classifying sharpness index, while a neural network (NN) model is developed using CFD data to predict the optimal feature parameter combination for classification performance. The results reveal that the rotor cage speed holds the most significant impact on both the cut size and classifying sharpness index. The optimal combination of feature parameters recommended by the neural network is v=8m/s, n=1200r/min, z=36, θ=40°, at which the cut size is 28.3 μm, a reduction of 9.0 % compared to the Taguchi experiment. In addition, the relative error between the cut size predicted by the neural network model and the CFD simulation is less than 4.5 %, indicating the reliability of the neural network model in predicting the optimal parameter combination of the classifying device.

Multi-objective optimization of hydrocyclones using meta-heuristic algorithms and preference-informed decision-making

Previous hydrocyclone optimizations often overlooked crucial objectives interactions, thereby weakening the overall system performance. This study presents a framework that integrates meta-heuristic algorithms with preference-informed decision-making to simultaneously optimize key performance objectives. Meta-heuristics identify comprehensive Pareto-optimal sets, while preference-informed decision-making evaluates each solution's overall separation performance according to specific separation preferences. Supported by computational fluid dynamics, the study quantifies the trade-off between optimal overall separation performance and pressure drop, enabling the attainment of optimal overall separation performance at any pressure drop within the Pareto-optimal set. Among the evaluated algorithms, the strength Pareto evolutionary algorithm 2 (SPEA2) stands out for its exceptional diversity and convergence. With this framework, the study circumvents excessive compromises on neglected but crucial objectives, especially highlighting the significant adverse effects of overlooking water split or cut size. Overall, this study provides an integrated approach for developing energy-efficient hydrocyclones that maximize overall separation performance tailored to specific separation requirements.

Productivity of elephant grass pakchong (Pennisetum purpureum cv Pakchong) and elephant grass taiwan (Pennisetum purpureum cv Taiwan) cultivated based on different stem cutting sizes

Abstract In Indonesia, elephant grass seeds used by farmers are in the form of cuttings or vegetative material. Currently, there is no standard for the cuttings used to produce high-productivity elephant grass. Therefore, research was conducted to determine the optimal size of cuttings for achieving good elephant grass productivity. The study was conducted in the field station area of Rancamaya, Bogor. A factorial group randomized design with 5 replications was employed for the research. The first factor was the type of elephant grass, consisting of 1) Pakchong and 2) Taiwan, while the second factor was the size of the cuttings, consisting of 1) 5 cm long cuttings, one node, 2) 10 cm long cuttings, one node, 3) 15 cm long cuttings, one node, and 4) control (two nodes as per usual farmer practice). The research results indicated that there was an interaction between the type of elephant grass and the size of cuttings for leaf length, fresh and dry leaf weight, dry stem weight, and total dry weight. The 5 cm cuttings of Pakchong had the highest fresh and dry leaf weights (P<0.05). The highest dry stem and total weight were obtained with the control size cuttings of Pakchong. The number of tillers was influenced by the size of cuttings, with the control size cuttings having the highest number of tillers, although not significantly different from the number of tillers for the 5 cm and 15 cm cuttings. The highest total fresh weight was obtained with the 5 cm cuttings and Pakchong. This study indicates that 5 cm cuttings can be used as cutting material to produce Pakchong and Taiwan with optimal forage production. Further research is needed to assess the forage quality.

Influence of Increasing Carcass Weights on Pork Carcass Characteristics and Traditional and Alternative Fabrication Yields

The objective was to characterize the effects of increasing carcass weight on pork carcass characteristics and yields from traditional and alternative fabrication methods, as well as evaluate the size of novel retail cuts. Pigs (n = 85) were slaughtered and divided into 3 hot carcass weight (HCW) categories: Average (99 to 109 kg), Heavy (116 to 126 kg), and Very Heavy (134 to 144 kg). Loin muscle area (LMA) and back fat depth were measured on all carcasses. Paired right and left sides were fabricated traditionally and alternatively (shoulder separation at the 4th/5th rib), respectively. From the alternative side, the serratus ventralis (SV) was removed from the cellar-trimmed butt, and the triceps brachii (TB) was removed from the picnic shoulder. All individual primals and subprimals were weighed for yield calculations. Data were analyzed using the MIXED procedure in SAS including the main effect of weight class, with sex and sire line as fixed blocking effects. Differences were considered significant at P ≤ 0.05. Regardless of fabrication method, whole primal and subprimal weights increased (P < 0.01) in heavier carcass weight classes compared with lighter classes, but when expressed as a percentage of chilled side weight, these increases did not often translate into meaningful differences in distribution of carcass weight. While the alternative shoulder-loin separation reduced loin and belly length, loins and bellies from heavier carcasses weighed more than those from carcasses typically produced in the U.S. pork industry today. Serratus ventralis weight was increased (P < 0.01) approximately 0.28 kg from Average to Very Heavy, while the TB weight was increased (P < 0.01) approximately 0.24 kg from Average to Very Heavy. At heavier weights, alternative fabrication of carcasses yielded novel cuts from the shoulder including the SV and TB that were of size to warrant further exploration as retail offerings.

Tight Lower Bounds for Directed Cut Sparsification and Distributed Min-Cut

In this paper, we consider two fundamental cut approximation problems on large graphs. We prove new lower bounds for both problems that are optimal up to logarithmic factors. The first problem is approximating cuts in balanced directed graphs. In this problem, we want to build a data structure that can provide (1 ± ε)-approximation of cut values on a graph with n vertices. For arbitrary directed graphs, such a data structure requires Ω(n 2 ) bits even for constant ε. To circumvent this, recent works study β-balanced graphs, meaning that for every directed cut, the total weight of edges in one direction is at most β times the total weight in the other direction. We consider the for-each model, where the goal is to approximate each cut with constant probability, and the for-all model, where all cuts must be preserved simultaneously. We improve the previous Ømega(n √β/ε) lower bound in the for-each model to ~Ω (n √β /ε) and we improve the previous Ω(n β/ε) lower bound in the for-all model to Ω(n β/ε 2 ). This resolves the main open questions of (Cen et al., ICALP, 2021). The second problem is approximating the global minimum cut in a local query model, where we can only access the graph via degree, edge, and adjacency queries. We prove an ΩL(min m, m/ε 2 k R) lower bound for this problem, which improves the previous ΩL(m/k R) lower bound, where m is the number of edges, k is the minimum cut size, and we seek a (1+ε)-approximation. In addition, we show that existing upper bounds with minor modifications match our lower bound up to logarithmic factors.

On conflict-free cuts: Algorithms and complexity

One way to define the Matching Cut problem is: Given a graph G, is there an edge-cut M of G such that M is an independent set in the line graph of G? We propose the more general Conflict-Free Cut problem: Together with the graph G, we are given a so-called conflict graph Gˆ on the edges of G, and we ask for an edge-cutset M of G that is independent in Gˆ. Since conflict-free settings are popular generalizations of classical optimization problems and Conflict-Free Cut was not considered in the literature so far, we start the study of the problem. We show that the problem is NP-complete even when the maximum degree of G is 5 and Gˆ is 1-regular. The same reduction implies an exponential lower bound on the solvability based on the Exponential Time Hypothesis. We also give parameterized complexity results: We show that the problem is fixed-parameter tractable with the vertex cover number of G as a parameter, and we show W[1]-hardness even when G has a feedback vertex set of size one, and the clique cover number of Gˆ is the parameter. Since the clique cover number of Gˆ is an upper bound on the independence number of Gˆ and thus the solution size, this implies W[1]-hardness when parameterized by the cut size. We list polynomial-time solvable cases and interesting open problems. At last, we draw a connection to a symmetric variant of SAT.

Study on the Separation Performance of a Two Cylindrical Section Hydrocyclone under Various Height Ratios.

Two cylindrical section hydrocyclones can suppress particle misplacement by regulating the circulation flow, but few researchers have investigated the effect of the cylindrical height ratio. In this paper, numerical simulations and physical tests were conducted to investigate the effect of height ratio on the particle motion behavior and separation performance of the two cylindrical section hydrocyclone. According to the numerical simulation results, with increasing height ratio, the separation cut size decreased, the separation accuracy and recovery rate of medium and coarse particles in the underflow increased, the coarse particle misplacement in overflow decreased significantly, and the proportion of medium particle circulation flow gradually increased. According to the test results, the number of misplaced fine particles in underflow could be effectively reduced when H1/H0 = 0.30. With increasing height ratio, the number of misplaced coarse particles in the overflow decreased and the classification efficiency of fine particles increased. The maximum separation efficiencies of medium and coarse particles could be obtained at H1/H0 values of 0.47 and 0.17, respectively. Therefore, increasing the height ratio could inhibit coarse particle misplacement in overflow and improve the separation performance of two cylindrical section hydrocyclones.

FSM: A Fine-Grained Splitting and Merging Framework for Dual-Balanced Graph Partition

Partitioning a large graph into smaller subgraphs by minimizing the number of cutting vertices and edges, namely cut size or replication factor, plays a crucial role in distributed graph processing tasks. However, many prior works have primarily focused on optimizing the cut size by considering only vertex balance or edge balance, leading to significant workload imbalance and consequently hindering the performance of downstream tasks. Therefore, in this paper, we address the dual-balanced graph partition problem that minimizes the cut size while simultaneously guaranteeing both vertex and edge balance. We propose a lightweight effective two-phase framework, namely fine-grained splitting and merging (FSM), which decomposes the graph into more and smaller partitions and then merges them. FSM offers the flexibility of integrating with various state-of-the-art single-balanced techniques. We develop two efficient algorithms Fast Merging and Precise Merging to enable trade-offs between computational efficiency and partitioning quality. Experimental results on large real-world graphs demonstrate that FSM achieves state-of-the-art cut size while maintaining dual balance. The runtime for downstream tasks PageRank, connected component, and diameter estimation, can be reduced by a large proportion, up to 9.43%, 11.35%, and 17.94%, respectively.

Effect of pulsating flow induced by a percussive drilling tool on cuttings transport in horizontal directional drilling—A CFD study

Cuttings deposition and removal has always been a key issue in horizontal directional drilling due to its correlation with numerous problems such as rate of penetration, reduction and stuck pipe.In this paper, the relationship between the impulse flow generated by a fluidic jet hammer and cuttings removal was discussed. A Eulerian-Eulerian two-fluid model was used to simulate the cuttings transport in horizontal wells on a sliding grid basis. Results show that the flow pulsation induced by a fluidic hammer contributes to easier cuttings transport. Compared to constant flow, impulse flow showed a 22.03% improvement in more optimal borehole cleaning with the same system inlet flow rate. In addition, the asymmetric flow pulsation was more sensitive to amplitude than the sinusoidal waveform pulsation flow, and as amplitude increased, the average exit flow rate of cuttings increased by 30.95%. Cuttings transport in annular is sensitive to rate of penetration, average velocity of pulsation, pulsation amplitude and cuttings size. The effect of pulsation frequency seems to be not much significant, probably because the frequency or other parameters used in this work did in the range of optimal particle-carrying frequency. These findings can provide references for the utilization of downhole pulsating fluids by drilling tools.