Split Processes Research Articles

Automated generation of digital models for manufacturing systems: The event-centric process mining approach

Digital and simulation models support the design and management of complex systems. However, system modelling is a time-demanding and knowledge-intensive activity. Moreover, modern manufacturing systems are subjected to frequent changes in production plans and subsequent reconfigurations. Therefore, the quick regeneration of the digital models is necessary to align digital twins and cyber-physical systems. This paper proposes a novel event-centric process mining paradigm, a process discovery algorithm, and a set of Key Performance Indicators for the fast and automated generation of digital models and their benchmarking. The discovery algorithm is based on the Event Relationship Graph of the conceptual model of the physical line. The algorithm is tested in four realistic systems of increasing complexity to verify the accuracy in modelling multi-product systems with re-entrant flows and random reworks in the presence of the assembly, disassembly, and split processes beyond the processing operations, and multi-operation workstations. The Event Relationship Graphs of the four systems are presented through the equivalent Petri nets models. The proposed approach is suitable for systems where the sensor positions are known and meaningful, like manufacturing systems, and it is effective for the quick automated generation of digital models for the activities of production planning and control as it requires a few seconds of computation time and a few hours of system observation.

Experiments and modeling of the thermal spray-chasing phenomenon during split injection processes

Spray chasing is a specific manifestation of the interaction between split injections, where the mass and heat transfer between the pilot and main sprays significantly influence fuel mixing and ignition processes. In this study, a spray-chasing model is developed and validated based on optical diagnostic results, aiming to theoretically support the development of injection strategies that are more environmentally adaptive and offer improved performance. A series of optical diagnoses of diesel split injection is performed in a constant volume combustion chamber using diffused back-illumination imaging and high-speed schlieren imaging. The extent of the spray-chasing phenomenon is modulated by regulating the injection dwell time (DT) and ambient temperature. For inert sprays, when the background temperature exceeds 790 K, the liquid spray-chasing phenomenon can be disregarded owing to the premature evaporation of the pilot spray. Although shortening the DT can promote the development and mixing of the main spray, the lack of evaporation in the pilot fuel pocket leads to a higher local fuel concentration in the interaction zone after spray chasing, which will hinder the subsequent ignition of the main spray. For reactive sprays, the variations in spray chasing patterns under different operating parameters are determined and their impact on the ignition process is evaluated by combining optical test results with theoretical models. Under cold start conditions, the ignition delay and ignition location of the main spray exhibit a non-monotonic trend with increasing injection dwell time. Optical diagnosis observes that compared to DT of 200 us and 1500 μs, the main spray exhibits both valley in ignition delay time and ignition location at DT = 900 μs. The spray-chasing model identifies approximately 1020 μs as the optimal theoretical DT, expected to best facilitate ignition of the main spray. However, under hot-start conditions, even though the spray-chasing mode varies with different injection dwell times, the ignition characteristics remain essentially unchanged due to the limited promotion effect of split injection on ignition.

Small Scale Plant of Desalination Using Multiple Tray Aerator and Two Different Membranes of Reverse Osmosis Using Low-Pressure Pump

The seawater is an abundant source that still not be utilized as potential raw water source to overcome the deficit of drinking water. This paper aims to design the small-scale desalination plant with the capacity of 2000 gpd for treating the brackish and seawater. There are two split processes, i.e., multi-tray aerator and filtration for reducing the Fe and Mn, while the two different type reverse osmosis membranes were used for desalinating process. Parameters used to verify the performance of small-scale plant are salinity and total dissolved solid for membranes, while the parameters for examining the pre-treatment results are TSS, BOD, pH, Fe, and Mn. The test results will be evaluated under the Regulation of The Minister of Health, Number 32/2017. The influence of pump pressure on flow will also be analysed. The results show that multi-tray aerator needs some improvement to reduce the Mn, and Fe. The two types of membranes could significantly reduce the salinity level up to 91.7%, from 22,900 ppm to 1200 ppm. The pump pressure needs to be replaced into the high-pressure pump to reduce the salinity level significantly.

Visual integration across fixation: automatic processes are split but conscious processes remain unified in the split-brain.

The classic view holds that when "split-brain" patients are presented with an object in the right visual field, they will correctly identify it verbally and with the right hand. However, when the object is presented in the left visual field, the patient verbally states that he saw nothing but nevertheless identifies it accurately with the left hand. This interaction suggests that perception, recognition and responding are separated in the two isolated hemispheres. However, there is now accumulating evidence that this interaction is not absolute; for instance, split-brain patients are able to detect and localise stimuli anywhere in the visual field verbally and with either hand. In this study we set out to explore this cross-hemifield interaction in more detail with the split-brain patient DDC and carried out two experiments. The aim of these experiments is to unveil the unity of deliberate and automatic processing in the context of visual integration across hemispheres. Experiment 1 suggests that automatic processing is split in this context. In contrast, when the patient is forced to adopt a conscious, deliberate, approach, processing seemed to be unified across visual fields (and thus across hemispheres). First, we looked at the confidence that DDC has in his responses. The experiment involved a simultaneous "same" versus "different" matching task with two shapes presented either within one hemifield or across fixation. The results showed that we replicated the observation that split brain patients cannot match across fixation, but more interesting, that DDC was very confident in the across-fixation condition while performing at chance-level. On the basis of this result, we hypothesised a two-route explanation. In healthy subjects, the visual information from the two hemifields is integrated in an automatic, unconscious fashion via the intact splenium, and this route has been severed in DDC. However, we know from previous experiments that some transfer of information remains possible. We proposed that this second route (perhaps less visual; more symbolic) may become apparent when he is forced to use a deliberate, consciously controlled approach. In an experiment where he is informed, by a second stimulus presented in one hemifield, what to do with the first stimulus that was presented in the same or the opposite hemifield, we showed that there was indeed interhemispheric transfer of information. We suggest that this two-route model may help in clarifying some of the controversial issues in split-brain research.

Heavy-traffic limits for parallel single-server queues with randomly split Hawkes arrival processes

AbstractWe consider parallel single-server queues in heavy traffic with randomly split Hawkes arrival processes. The service times are assumed to be independent and identically distributed (i.i.d.) in each queue and are independent in different queues. In the critically loaded regime at each queue, it is shown that the diffusion-scaled queueing and workload processes converge to a multidimensional reflected Brownian motion in the non-negative orthant with orthonormal reflections. For the model with abandonment, we also show that the corresponding limit is a multidimensional reflected Ornstein–Uhlenbeck diffusion in the non-negative orthant.

Anytime User Engagement Prediction in Information Cascades for Arbitrary Observation Periods

Predicting user engagement -- whether a user will engage in a given information cascade -- is an important problem in the context of social media, as it is useful to online marketing and misinformation mitigation just to name a couple major applications. Based on split population multi-variate survival processes, we develop a discriminative approach that, unlike prior works, leads to a single model for predicting whether individual users of an information network will engage a given cascade for arbitrary forecast horizons and observation periods. Being probabilistic in nature, this model retains the interpretability of its generative counterpart and renders count prediction intervals in a disciplined manner. Our results indicate that our model is highly competitive, if not superior, to current approaches, when compared over varying observed cascade histories and forecast horizons.

Midterm Outcomes of Muscle-Preserving Posterior Lumbar Decompression via Sagittal Splitting of the Spinous Process: Minimum 5-Year Follow-up.

To overcome several disadvantages of conventional laminectomy for degenerative lumbar spinal stenosis (DLSS), several types of minimally invasive surgery have been developed. The purpose of the present study was to report the clinical and radiological mid-term outcomes of spinous process-splitting decompression (SPSD) for DLSS. Seventy-three consecutive patients underwent SPSD between September 2014 and March 2016. Of these, 42 (70 segments) who had at least 5 years of follow-up were analyzed retrospectively. The visual analog scale for back pain and leg pain, Oswestry disability index, and walking distance without resting were scored to assess clinical outcomes at the preoperative and final follow-up. A subgroup analysis was performed according to the union status of the split spinous processes (SPs). For radiological outcomes, slip in the neutral position as a static parameter, anterior flexion-neutral translation, and posterior extension-neutral translation as a dynamic parameter were measured before and at the final follow-up after surgery. Spinopelvic parameters were also measured. Reoperation rate at the index levels was investigated, and predictive risk factors for reoperation were evaluated using multivariate logistic regression. Survival analysis was performed with reoperation as the endpoint to estimate the longevity of the SPSD for DLSS. All clinical outcomes improved significantly at the final follow-up compared to those at the initial visit (p < 0.05). The clinical outcomes did not differ according to the union status of the split SP. There were no cases of definite segmental instability and no significant changes in the static or dynamic parameters after surgery. Sacral slope and lumbar lordosis increased, and pelvic tilt decreased significantly at the follow-up (p < 0.05), despite no significant change in the sagittal vertical axis. The mean longevity of the procedure before the reoperation was 82.9 months. Five patients (11.9%) underwent reoperation at a mean of 52.2 months after the SPSD. There were no significant risk factors for reoperation; however, the preoperative severity of foraminal stenosis had an odds ratio of 7.556 (p = 0.064). SPSD for DLSS showed favorable clinical and radiological outcomes at the mid-term follow-up. SPSD could be a good surgical option for treating DLSS.

On the splitting and aggregating of Hawkes processes

AbstractWe consider the random splitting and aggregating of Hawkes processes. We present the random splitting schemes using the direct approach for counting processes, as well as the immigration–birth branching representations of Hawkes processes. From the second scheme, it is shown that random split Hawkes processes are again Hawkes. We discuss functional central limit theorems (FCLTs) for the scaled split processes from the different schemes. On the other hand, aggregating multivariate Hawkes processes may not necessarily be Hawkes. We identify a necessary and sufficient condition for the aggregated process to be Hawkes. We prove an FCLT for a multivariate Hawkes process under a random splitting and then aggregating scheme (under certain conditions, transforming into a Hawkes process of a different dimension).

Effects of Multi-Stage Split Injection on Efficiency and Emissions of Light-Duty Diesel Engine

The efficiency of light-duty diesel engines should be improved for further emissions regulation. Multi-stage split injection with five injection events was investigated for improvement in efficiency at low-load conditions. The injection timing and quantity were adjusted to achieve a smooth in-cylinder pressure rise and continuous heat release. The multi-stage split injection was compared to injection strategies involving two-pilot and single-main injections. A 0.5 L single-cylinder diesel engine experiment was conducted under low-load conditions. Two multi-stage split injection processes with different combustion phases were developed. The multi-stage split injections yielded a smooth in-cylinder pressure trace and a lower peak heat release rate than the two-pilot injection process. The combustion duration was shorter for multi-stage split injection with an advanced combustion phase, and the fuel consumption was reduced by 1.78% with lower heat transfer, exhaust heat, and combustion loss. The multi-stage split injection flame penetration was shorter than the two-pilot injections. The shorter flame penetration and lower tip velocity reduced the heat transfer to the combustion chamber. The PM emissions were also reduced by 30% under the same NOx emissions, because increased PM oxidation and divided fuel injection prevented flame diffusion and improved air utilization.

Split Heat Pump Distillation Based on Two‐Stage Compression for Separating an Acetone‐Water Mixture

AbstractThere is a constant concentration zone for acetone‐water mixtures, and the average relative volatility of the two components in the constant concentration zone is only 1.41, so the energy consumption of the conventional distillation process is high. Two kinds of split mechanical vapor recompression (MVR) heat pump distillation processes, i.e., single‐stage and two‐stage compression processes, were proposed to separate acetone‐water mixtures. The thermodynamic data of the mixture were calculated and modules of Aspen Plus were used to simulate the distillation column and steam compressor. Taking the minimum total annual cost as the objective function, the conventional MVR and the two split MVR heat pump distillation processes were simulated and optimized. Compared with the conventional process, the MVR heat pump distillation process had greater economic advantages, and the split heat pump distillation (SHPD) with two‐stage compression was superior to the other MVR heat pump distillation processes.

Economic and thermodynamic comparison of enhanced recycle split vapor processes for ethane recovery under different rich feed compositions

Based on the recycle split vapor (RSV) process for ethane recovery, this paper proposes three primary improved processes, and in China, five rich feed compositions are selected as preliminary data. We use economic and thermodynamic analysis methods to compare and analyze RSV and its improved processes comprehensively. The comparative analysis results show that: ①The enhanced techniques all show a certain energy-saving effect, especially it is evident for the modified recycle split vapor with liquid flashing (RSVF) process to save energy; ②The geometric structure of the plate-fin heat exchanger inside the cold box significantly affects its capital cost, the design of the plate-fin heat exchanger in the corresponding cold box is basically the same, with slight differences under different feed conditions; ③The compressors and expander are the most prominent investment types of equipment, and their purchase costs accounting for about 70% of the total purchased equipment costs. The values of financial net present value (FNPV) of the improved processes are all greater than zero under the operating conditions in this study, which can meet the profitability required by the benchmark rate of return. The project has a more significant return on investment and shorter return time; ④The improved processes under five feeds show excellent performance and adaptability: the larger GPM (gallons per thousand cubic feet) values of feed compositions, the more apparent the energy saving. The main contributors to the exergy destruction are towers, compressors, expander, and cold boxes; ⑤Compared with the improved recycle split vapor with gas extraction (RSVG) and supplemental rectification with compression and recycle split vapor (SRCR) processes, the improved RSVF process has a better pre-separation effect for heavy hydrocarbons by adding a flash separator, which makes this process have less exergy destruction and enormous energy-saving potential.

«Чисписты»: раскол в аргентинской компартии в 20-е годы

In the 1920s, the Communist Party of Argentina (PC) went through three major crises that ended in split processes. This article analyzes the origins and development of the second of these factional struggles, which led to the formation of a new political organization, the Com-munist Workers Party. The dissident fraction was called "chispistas" in reference to the name of its newspaper. We are interested in studying the links that the new party established with the labor movement and its union structures. The intention is to contribute to a better under-standing of the communist experience and to contribute to the recon-struction of the history of the Argentine left in its connection with the labor movement.

PROFILE OF SAWMILLS IN THE UBÁ FURNITURE HUB IN THE STATE OF MINAS GERAIS

The objective of this work was to identify, diagnose and characterize the sawmills in four municipalities in the State of Minas Gerais (Divinésia, Senador Firmino, Brás Pires and Dores do Turvo) that provide lumber for the industries in the Furniture Hub in Ubá, State of Minas Gerais. A semi-structured questionnaire with open questions, answered in loco and accompanied by a responsible person (interviewer), with information on the identification of the potentialities and fragilities of the local lumber sector as well as to know the raw material (logs), the wood split processes, the internal management, the qualification of the employees, the machinery, products, market and prospects of the sector in these municipalities. It was found that Eucalyptus wood is the most used. The diameter of the logs is shown as the factor that affects the yield in 100% of the analyzed sawmills, where cracking and variability of the logs are the main difficulties of working with the raw material. The lumber sector in the analyzed municipalities needs a greater qualification, both managerial and technical, to improve the activity. In addition, it is necessary to better organize the companies related to the lumber sector through associations and support from local entities and greater exposure of the products to the local consumers.

Comprehensive comparison of enhanced recycle split vapour processes for ethane recovery

The recycle split vapour (RSV) process is used for ethane recovery all over the world. However, improvements in RSV are required to treat unconventional feed gases under special conditions. In this paper, we propose three enhanced processes: RSV with propane refrigeration and pre-pressurization (RSVPP), RSV with propane and ethylene combined refrigeration (RSVPE) and RSV with propane and mixed refrigerant refrigeration (RSVPM). A comprehensive comparative analysis of the performances of these processes is carried out using conventional RSV as a reference. All the enhanced processes exhibit excellent performance in terms of the ethane recovery rate. However, the characteristics of each process cannot be differentiated using a single measure to compare the processes. The aim of this study is to evaluate the modified RSV processes in terms of economy, energy consumption and exergy. Thus, the advantages and disadvantages of each enhanced process are highlighted, enabling researchers to distinguish among the three proposed processes from different perspectives.

Analysis of a rich vapor compression method for an ammonia-based CO2 capture process and freshwater production using membrane distillation technology

Post-combustion capturing of CO2 through chemical solvent absorption is a promising technique for reducing the CO2 emissions from fossil fuel power plants. However, the energy penalty associated with the absorbent regeneration continues to be a critical challenge in the chemical solvent absorption process. In this study, the operating parameters of ammonia-based CO2 capture were optimized to reduce the energy penalty. This optimized process was considered a base process to which process modifications were added, with the goal of further reducing the energy consumption. These process modifications included absorber inter-cooling and rich vapor compression (RVC) combined with cold solvent split (CSS) processes. The combined RVC and CSS process was compared with the base process and advanced NH3-based CO2 capture processes, such as the rich split process and the inter-heating process. Compared to the base process, the combined process reduced the energy requirements by 20.2%, which was higher than the 11.6% and 8.26% energy reductions obtained via the rich split and inter-heating processes, respectively. The combined process was also compared with MEA-based process modifications. The energy savings from the combined process were higher than those of the MEA-based process modifications. To estimate the trade-offs between the energy savings resulting from the combined process vs. the capital cost of the additional equipment required, the Aspen Capital Cost Estimator (ACCE) was used. The results showed that the combined process saved $0.707 million per year. Furthermore, a membrane distillation (MD) technology was integrated with the CO2 capture unit to produce freshwater. This additional process produced freshwater at a rate of 719.240 m3/day at a feed stream temperature to the MD unit of 35.66 ℃.

Ammonia-based CO2 capture parameters optimization and analysis of lean and rich vapor compression processes

Carbon dioxide (CO2) capture through chemical solvent absorption process is the most favourable and well-proven technique to reduce CO2 emission. However, in this technique, the energy penalty correlated with absorbent regeneration is a critical challenge. To reduce energy consumption, the operating parameters in NH3-based CO2 capture process were optimized. Then flowsheet modifications including rich vapor compression (RVC) and lean vapor compression (LVC) were proposed for the first time in the NH3-based CO2 capture process. Both the LVC and RVC schemes were combined with cold solvent split (CSS) process to further reduce the energy requirements. Moreover, the LVC and RVC processes of this study were also compared with the advanced NH3-based and MEA-based LVC and RVC processes with respect to energy reduction. The optimized process was considered as a base process and it was compared with the modified processes. The RVC and LVC combined with CSS process reduced the reboiler duty by 26.7% and 19%, respectively. These energy savings are much higher than that of 11.6% and 8.26% energy savings of the advanced NH3-based rich split and inter-heating processes, respectively. The total equivalent energy savings of LVC, RVC, LVC with CSS, and RVC with CSS processes in this study were about 6.4%, 18.1%, 3.4%, and 15%, respectively, which are higher than 3.4% and 8.5% energy savings of MEA-based LVC with CSS and RVC with CSS processes, respectively. Furthermore, these combined processes can also avoid the use of a condenser.

Restoration of the Spinous Process Following Muscle-Preserving Posterior Lumbar Decompression via Sagittal Splitting of the Spinous Process.

BackgroundIn lumbar spinal stenosis, spinous process-splitting decompression has demonstrated good clinical outcomes with preservation of the posterior ligamentous complex and paraspinal muscles in comparison to conventional laminectomy, but the radiological consequence and clinical impact of the split spinous processes have not been fully understood.MethodsSeventy-three patients who underwent spinous process-splitting decompression were included. The bone union rate and pattern were evaluated by computed tomography performed 6–18 months after surgery and compared among subgroups divided according to the number of levels decompressed and the extent of spinous process splitting. The bone union pattern was classified into three categories: complete union, partial union, and nonunion. The visual analog scale (VAS) score, Oswestry disability index (ODI), and walking distance assessed both before and 24–36 months after surgery were compared among subgroups divided according to the union pattern of the split spinous process.ResultsOverall, the rates of complete union, partial union, and nonunion were 51.7%, 43.2%, and 5.1%, respectively. In the subgroup with partial splitting of the spinous process, the rates were 85.7%, 14.3%, and 0%, respectively; those of the subgroup with total splitting of the spinous process were 32.9%, 59.2%, and 7.9%, respectively. With single-level decompression, a higher rate of union was observed compared with multilevel decompression. The VAS, ODI, and walking distance were significantly improved after surgery and did not differ according to the degree of union of the split spinous process.ConclusionsWe found that the single-level operation and partial splitting of the spinous process were favourable factors for obtaining complete restoration of the posterior bony structure of the lumbar spine in spinous process-splitting decompression.

Pressure-Based Approach to Estimating the Injection Start and End in Single and Split Common Rail Injection Processes

Fuel injection timing is an important control parameter for engine combustion optimization and emissions control. However, the actual fuel injection timing is different from the nominal one commanded by the electronic control unit, due to the system hydraulic lag or the possible communication malfunction. In this study, a simple estimate approach based on the injector inlet pressure is proposed to capture four critical characteristic instants at the start and end of injection. The critical characteristic moments estimated using this pressure-based approach are validated against those determined by the actual injection rate profiles, in the context of different single or split injection processes. The comparison revealed that the characteristic injection moments estimated by the injector inlet pressures and those determined by the actual injection rate profiles have a satisfactory agreement, certifying the broad applicability and reliability of this pressure-based approach in the detection of the real fuel injection start and end time.

Morphology‐Controllable Synthesis of Cubic‐Structured In2O3 Particles with Enhanced NO2 Gas Sensitivity

A hydrated basic sulfate precursor for In2O3 is facilely prepared from the mixed indium nitrate and ammonium sulfate solutions via means of single‐step hydrolysis precipitation at a relatively low synthetic temperature of ≈60 °C, which subsequently converts to an oxide powder via pyrolyzing. The morphologies of the precursor and oxide can be controlled via adjusting volume fractions of ethanol‐water solvents. The pure water solvent in the reaction system leads to a thick two‐dimension plate‐like precursor and its oxide generally retains the original shape, while the addition of ethanol up to the volume fraction of 75% in the mother liquor is able to effectively reduce the thickness of the plates to result in well‐dispersed oxide powder with round morphology via partial split, full collapse, and particle growth processes. The as‐prepared In2O3 gas sensors have rapid response and recovery time to trace NO2 and the In2O3 gas sensor derived from the well‐dispersed oxide powder has a rather higher sensitivity than the agglomerated one.

A New Fixation Technique for French-Door Cervical Laminoplasty: Surgical Results With a Minimum Follow-up of 6 Years.

A case series of 5 patients with multilevel cervical myelopathy treated by French-door cervical laminoplasty (FDCL) and use of unicortical iliac crest graft as spacer fixed with titanium miniplates and screws is described. To report a minimum of 6-year follow-up results of our new plate-screw fixation technique for FDCL. Hardware-assisted laminoplasty has the potential advantage of preventing restenosis by holding the laminar door "open" while healing progresses and also prevents spacer dislodgement. The use of titanium miniplates as internal fixation device for FDCL by our novel technique has not been reported. Five patients suffering from multilevel cervical myelopathy harboring constitutionally narrow cervical canal (3) and multilevel cervical spondylotic myelopathy (2) who underwent 2-3 level FDCL and followed up prospectively for 6 years is presented. Modified Kurokawa and colleague's technique of FDCL was performed and autologous iliac crest bone graft was interposed between the sagittaly split spinous processes. A 12- to 15-hole titanium miniplate was contoured into a trapezoidal shape to sit flush with the posterior elements. The plate was anchored to bone graft and posterior elements with screws and patients mobilized without any external orthosis. The mean follow-up was 90.5 months. The mean improvement in Neck disability index at final follow-up was 35% and mean improvement in Visual analog scale was 4 points. Japanese orthopaedic association score improved from a mean of 10 to a mean of 14.8 postoperatively. The final outcome was good (3) and excellent (2) by Odom's criteria. All patients improved to Nurick's grade 0 or I and reported significant relief from their myelopathic symptoms and axial neck pain. There were no postoperative hardware-related complications or pseudoarthrosis. Titanium miniplates are excellent devices for stabilizing the interspinous spacers used in FDCL. They prevent cervical canal deformation, restenosis, spacer dislodgement and are durable, cost-effective in facilitating early mobilization at intermediate-term follow-up of 6 years.