Total Production Time Research Articles

Machine configuration and workload balancing of modular placement machines in multi-product PCB assembly

ABSTRACTA popular gantry-type placement machine includes several interconnected, autonomously operating component placement modules and the machine was designed so as to able to use different kinds of placement heads and vacuum nozzles in the modules, which can be easily changed. Although this increases the flexibility of the production line, the reconfiguration phases of the modules may be unproductive and one should keep them to a minimum. In addition, the production times can be shortened by balancing the workloads of the machine modules. Here, a two-step optimisation method for the machine reconfiguration and workload balancing in the case of multiple Printed Circuit Borad (PCB) batches of different sizes and PCB types is presented. The objective is to minimise the total production time, and keep the machine configuration the same for all batches. The proposed algorithm is iterative and it applies integer programming for the workload balancing along with an evolutionary algorithm that searches for the best machine configuration. In experiments, for single PCB types the proposed algorithm obtained optimal or near optimal solutions. For multiple PCB types the solutions favour the PCB types that have a bigger production time due to greater batch sizes, but the total production time is still close to optimal.

Current state mapping of the supply chain in engineering procurement construction (EPC) project: a case study

Engineering Procurement Construction (EPC) is a construction model that integrated the work between engineering, procurement, and construction. The EPC project is usually applied in petroleum work. One of the important aspects of success key in this project is the supply chain management (SCM). The high level of complexity of work as well as the integration of the construction phase needs to be mapped how the supply chain in this project. This paper used Value Stream Mapping (VSM) method to explain the procurement processes for easier understanding and problem identification. It is illustrated in the procurement process behaviour within a specific period from the total production time. This paper describes a case study performed on EPC 1 Banyu Urip Project. VSM presented real-time data to deliver the processes, material, and any other constraint relevant to the procurement process on EPC projects. Based on a case study on pipe material, the procurement process from upstream to downstream took 21 weeks. It was a waste of time to look for solutions. The recommended solutions use the local vendors, involve suppliers early and provide input into engineering designs, and good communication between supply chain participants.

Patient-specific three-dimensional printing for pre-surgical planning in hepatocellular carcinoma treatment

Recently, three-dimensional (3D) printing has shown great interest in medicine, and 3D printed models may be rendered as part of the pre-surgical planning process in order to better understand the complexities of an individual's anatomy. The aim of this study is to investigate the feasibility of utilising 3D printed liver models as clinical tools in pre-operative planning for resectable hepatocellular carcinoma (HCC) lesions. High-resolution contrast-enhanced computed tomography (CT) images were acquired and utilized to generate a patient-specific 3D printed liver model. Hepatic structures were segmented and edited to produce a printable model delineating intrahepatic anatomy and a resectable HCC lesion. Quantitative assessment of 3D model accuracy compared measurements of critical anatomical landmarks acquired from the original CT images, standard tessellation language (STL) files, and the 3D printed liver model. Comparative analysis of surveys completed by two radiologists investigated the clinical value of 3D printed liver models in radiology. The application of utilizing 3D printed liver models as tools in surgical planning for resectable HCC lesions was evaluated through kappa analysis of questionnaires completed by two abdominal surgeons. A scaled down multi-material 3D liver model delineating patient-specific hepatic anatomy and pathology was produced, requiring a total production time of 25.25 hours and costing a total of AUD $1,250. A discrepancy was found in the total mean of measurements at each stage of production, with a total mean of 18.28±9.31 mm for measurements acquired from the original CT data, 15.63±8.06 mm for the STL files, and 14.47±7.71 mm for the 3D printed liver model. The 3D liver model did not enhance the radiologists' perception of patient-specific anatomy or pathology. Kappa analysis of the surgeon's responses to survey questions yielded a percentage agreement of 80%, and a κ value of 0.38 (P=0.24) indicating fair agreement. Study outcomes indicate that there is minimal value in utilizing the 3D printed models in diagnostic radiology. The potential usefulness of utilizing patient-specific 3D printed liver models as tools in surgical planning and intraoperative guidance for HCC treatment is verified. However, the feasibility of this application is currently challenged by identified limitations in 3D model production, including the cost and time required for model production, and inaccuracies potentially introduced at each stage of model fabrication.

Productivity improvement through a sequencing generalised assignment in an assembly line system

This paper considers the assignment of heterogeneous workers to workstations of an assembly line in order to minimise the total production time. As the structure of the system implies that each of the workstations needs at least one worker, thus the problem can be considered as a generalised assignment problem (GAP). The objective is to perform an efficient human resource planning for a specified horizon consisting of several periods. Hence, we present an extension of the generalised assignment problem, consisting of a set of GAPs (one for each planning period) in which each GAP depends on the previous ones. A mixed integer mathematical model is presented for this sequencing assignment problem. The model is solved by an exact algorithm using Gurobi solver. It is proved that the problem is NP-hard and solving the medium and large size instances is not possible by the exact algorithms. Hence, two matheuristic approaches based on the disaggregated formulation of GAP are proposed. The first approach solves the problem through two sub-problems as the transportation formulation and assignment formulation. The second approach solves the problem by decomposition of the problem into several classical GAPs. The approaches are examined by a total of 27 instances. The results illustrate the efficiency of the proposed algorithms in the computational time and accuracy of the solutions.

EMPIRICAL / THEORETICAL PROPOSAL FOR THE PRODUCTION OF BIODIESEL

The present manuscript represents the projection of laboratory experiments in a theoretical reactor projected for the production of biodiesel. The objectives of this project were: production of biodiesel in less time; to reduce the energy consumption into the production of biodiesel; Non-dependence of the reaction kinetics from the reaction's temperature and high conversion rates of raw material into the final product with transesterification reactions performed at stoichiometric limits. The results indicate that the use of a single reaction vessel to perform several stages of production without the transfer of the total mass of fuel fluid between several vessels reduces the total production time. The reaction time was also optimized with the use of an appropriate monitoring system. Performing the reactions near the stoichiometric limits reduced the refining time of the final product, as there are fewer raw materials to be removed from the final product. Monitoring of the reaction with real-time LASER spectroscopy allowed initiating the reaction at room temperature and increasing the supply of energy (heat) throughout the reaction, reducing the energy consumption during the reaction, and the moment of chemical balance was detected with the monitoring system.

Comparison of Nursing Staff Calculation Based on the Time and Motion Study and Douglas Method

Introduction: The increase of the quality of service requires human resource with good quality and quantity. In health service, nursing staff need can be calculated by using many methods, such as Gillies method, ratio method, nursing workshop method, Thailand and Philippine method, Nina method, and Douglas method. Besides those six methods, nursing staff need can be calculated by calculating worktime and workload. This method is called Time and Motion Study. Douglas method is used to calculate nursing staff need at IRNA Bedah A Dr. Soetomo Hospital. The objective of this study was to compare the calculation of nursing staff need using Douglas method and Time and Motion Study. Method: This study used descriptive design with observational approach. Samples, taken by total sampling, were 12 nurses at IRNA Bedah A Dr. Soetomo hospital for Time and Motion Study and all patients at IRNA Bedah A. Data for Douglas method were collected by using classification of patient’s dependence into 3 categories, i.e; self care, partial care, and total care. Data for Time and Motion Study were collected by using observation of nurse’s activities and calculate nurse’s worktime and nurse’s workload. The results showed that according to Douglas method, IRNA Bedah A needed 16 nurses, and according to Time and Motion Study, IRNA Bedah A needed 14 nurses. The mean of patient’s dependence in one week was 13 patients with self care, 3 patients with partial care, and 4 patients with total care. Result: Total productive time of the nurses at IRNA Bedah A was 3.83 hours in the morning, 2.37 hours in the afternoon, and 5.25 hours at night. Nurse’s workload at IRNA Bedah A was 34.62%. It can be concluded that calculation by using method Douglas shows that IRNA Bedah A needs more nurses compared with calculation by using Time and Motion Study. Discussion: Time and Motion Study is more effective than Douglas method to calculate nursing staff need. Most patients at IRNA Bedah A is self care. Most nurse’s activity at IRNA Bedah A is non-productive activity. Most of the nurse’s activities at IRNA Bedah A have done based on the standard of procedure. Nurse’s workload at IRNA Bedah A is underload.

A Productivity Improvement of an Assembly Line through Line Balancing and Automated Work-Part Feeder

The purpose of this paper is to improve line productivity using line balancing technique and a reduction of work variation using an automated part feeder. This is due to the fact that the conventional assembly line manually feeds a part on to the production line by a worker. The feeding cycle is not constant and varies from time to time. Thus, the production rate is not constant and varied by the worker feeding speed. In addition, the assembly line itself does not fully balance. The operation time of each station is not well designed; as a result, all of the stations but the bottle-neck one experience an idle time. The balance efficiency is only at 40.33 percent which means that 59.67 percent of the total production time is balanced delay. Once the automated feeding machine which a buffer is designed and implemented. The cycle time can be set at 6 sec. and with the line balance technique the operator can be reduced from 11 to 9 persons. As a result, the productivity is substantially increasing around 138 percent and the new balance efficiency is 85.12 percent.

3D Printers Provide a Window into the Heart.

Performing a transcatheter aortic valve replacement (TAVR) on a patient with congenital heart disease can force an interventional cardiologist to navigate uncharted anatomic territory. When the patient’s anatomy is complex, procedures such as placing a new heart valve can take longer and are associated with a higher risk for various complications. However, some cardiologists are turning to a new tool to help them prepare for such complex procedures—three-dimensional (3D) printers, which can use computed tomography scans to generate a model of the patient’s precise anatomy to prepare for the surgery. “The 3D printing allows us to have a 3D model that can be held in hand and shown to the interventional cardiologists and surgeons doing the procedure,” said Ron Blankstein, MD, codirector of the Cardiovascular Imaging Training program at Brigham and Women’s Hospital in Boston and Associate Professor of Medicine and Radiology at Harvard Medical School. “It is particularly useful in cases where the anatomy is not straightforward.” These 3D printers are becoming a fixture at many academic centers, where the printers and expert staff are often hired to help convert imaging into 3D models that can be used by surgeons and interventional cardiologists preparing for many types of surgeries and procedures. In addition to clinical applications, the technology is also being applied in basic research where scientists use it to print living cells into complex 3D structures called organoids, which re-create many features …

Natural frequency optimization of vehicle components using the interior search algorithm

Abstract In the automotive industry, optimum design must be achieved to compete with strong competitors. Thus, it is aimed to reduce the cost, increase the quality and reduce the total production time. In this study, the natural frequency optimization of a vehicle sliding door linkage used to open and close the sliding doors on vehicles was made. In the optimization study for determining the optimum design model of the vehicle sliding door linkage, natural frequency was increased by 22.8 % using internal search algorithm.

Mixed‐Integer Linear Programming on Work‐Rest Schedule Design for Construction Sites in Hot Weather

AbstractAn appropriate design of work‐rest schedule is recognized as an efficient way in providing better ergonomic environment, improving labor productivity as well as safety. Construction workers usually undertake physically demanding tasks in an outdoor environment, with awkward postures and repetitive motions. This study proposes a mixed‐integer linear programming approach to optimize the work‐rest schedule for construction workers in hot weather for the objective of maximizing the total productive time. The model takes into consideration the physical and physiological conditions of the workers, the working environment, the nature of the jobs and the minimum rest duration of the government regulation. The results of numerical experiments show that the proposed model outperforms a default work‐rest schedule by up to 10% in terms of total productive time. This implies considerable cost savings for the construction industry.

Investigating the impact of α-amylase, α-glucosidase and glucoamylase action on yeast-mediated bread dough fermentation and bread sugar levels

Wheat flour is generally supplemented with α-amylases to increase maltose levels in bread dough and increase loaf volume. While the preference of yeast for glucose and fructose over maltose as substrate for fermentation is well documented, the impact of maltose versus glucose producing enzymes on bread dough fermentation kinetics and bread sugar levels is ill documented. Hence the impact of α-amylase, α-glucosidase and glucoamylase action on both aspects was investigated. Glucoamylase and α-amylase increase the total fermentable sugar content of dough, while α-glucosidase only affects the glucose/maltose ratio. Due to their effect on total fermentable sugar levels, addition of α-amylase or glucoamylase prolongs the total productive fermentation time, while this is not the case for α-glucosidase. In contrast to α-amylase, both glucoamylase and α-glucosidase supplementation leads to higher CO2 production rates during the initial stages of fermentation. In the final bread product, different sugar levels are observed depending on the dosage and type of starch-degrading enzyme. The results of this study imply that long and short fermentation processes benefit from α-amylase and α-glucosidase addition, respectively, while glucoamylase supplementation is suitable for both long and short fermentation times.

Effects of ingredients ratio on physicochemical properties of convective-microwave nutritious dried rice meal

During emergency situation, such as natural disasters or war, diseases outbreak can occur due to lack of nutrition. Due to this issue, a wholesome dried rice meal (DRM) was conceptualised as emergency, quick, nutritious, functional and comforting food for natural disaster and war victims, particularly during the critical period of post-disaster or war period. The DRM was designed so that it can be consumed as dried cracker or semi-solid porridge. The objective of this study was to evaluate the effect of rice (100 g and 200 g), minced chicken meat (30 g and 40 g) and mixed vegetables (25 g and 35 g) ratio on the energy content, vitamin C, and expansion ratio of convective-microwave DRM. The convective-microwave drying method was chosen for DRM preparation to obtain the final product with specific puffing condition which enhances rehydration process and also to shorten the total production time of DRM. The experiments were conducted using factorial design. The experimental results showed that the highest DRM energy content of 1.60 kCal could be achieved by cooking 200 g rice with 40 g minced chicken meat and 25 g mixed vegetables. The DRM with highest vitamin C content of 0.018 g was achieved using 100 g, 30 g minced chicken meat and 25 g mixed vegetables. The DRM with the highest expansion ratio of 1.13 was achieved using 100 g rice, 30 g minced chicken meat and 25 g mixed vegetables. Empirical models for predicting energy contents, vitamin C and expansion ratio of the DRM were also obtained.

Rapid vacuum sintering: A novel technique for fabricating fluorapatite ceramic scaffolds for bone tissue engineering.

Macroporous bioceramic scaffolds are often fabricated via the foam replica technique, based on polymeric foam impregnation with a glass slurry, followed by slow heat treatment to allow for drying, polymeric burnout, and sintering of the glass particles. As a consequence, the process is time consuming and complicated by concurrent crystallization of the glass, often leading to incomplete sintering. Our goal was to investigate the effect of heating rate on sintering behavior, architecture, and mechanical properties of fluorapatite-based glass and glass-ceramic scaffolds. Glass scaffolds were prepared and sintered by rapid vacuum sintering (RVS) at 785°C under vacuum at a fast heating rate (55°C/min.) or without vacuum at a slow heating rate (2°C/min.). Two additional groups were further crystallized at 775°C/1 h. XRD confirmed the presence of fluorapatite for crystallized scaffolds. All groups presented interconnected porosity with a pore size in the 500 μm range. Scaffolds produced by RVS exhibited an excellent degree of sintering while scaffolds produced by slow sintering were incompletely sintered. The mean compressive strength was significantly higher for the RVS groups (1.52 ± 0.55 and 1.72 ± 0.61 MPa) compared to the slow-sintered groups (0.54 ± 0.30 and 0.45 ± 0.26 MPa). Meanwhile, the total production time was reduced by more than 12 h by using the RVS technique. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 291-299, 2018.

Photoperiod, Irradiance, and Temperature Affect Echinopsis ‘Rose Quartz’ Flowering

Photoperiod, irradiance, cool temperature (5 °C), and benzyladenine (BA) application effects on Echinopsis ‘Rose Quartz’ flowering were examined. Plants were placed in a 5 °C greenhouse under natural daylight (DL) for 0, 4, 8, or 12 weeks, then moved to a 22/18 °C (day/night temperature) greenhouse under short days (SD, 8-hour DL) plus 0, 25, 45, or 75 μmol·m−2·s−1 supplemental lighting (0800–1600 hr; 8-hour photoperiod), long days (LD) delivered with DL plus night-interruption lighting (NI) (2200–0200 hr), or DL plus 25, 45, or 75 μmol·m−2·s−1 supplemental lighting (0800–0200 hr) for 6 weeks. Plants were then grown under DL only. Percent flowering plants increased as irradiance increased from 0–25 to +75 μmol·m−2·s−1 on uncooled plants, from 0% to 100% as 5 °C exposure increased from 0 to 8 weeks under subsequent SD and from 25% to 100% as 5 °C exposure increased from 0 to 4 weeks under subsequent LD. As 5 °C exposure duration increased from 0 to 12 weeks (SD-grown) and from 0 to 8 weeks (LD-grown), flower number increased from 0 to 11 and from 5 to 21 flowers per plant across irradiance treatments, respectively. Total production time ranged from 123 to 147 days on plants cooled from 8 to 12 weeks (SD-grown) and from 52 to 94 days on plants cooled for 0–4 weeks to 119–153 days on plants cooled for 8–12 weeks (LD-grown). Flower life varied from 1 to 3 days. BA spray application (10–40 mg·L−1) once or twice after a 12-week 5 °C exposure reduced flower number. Flower development was not photoperiodic. High flower number (17–21 flowers/plant) and short production time (including cooling time, 120–122 days) occurred when plants were grown at 5 °C for 8 weeks, then grown under LD + 45–75 μmol·m−2·s−1 for 6 weeks (16 hours; 10.9–12.8 mol·m−2·d−1) at a 22/18 °C day/night temperature. Taken together, Echinopsis ‘Rose Quartz’ exhibited a facultative cool temperature and facultative LD requirement for flowering.

Electrosprayed Myocet-like Liposomes: An Alternative to Traditional Liposome Production.

Although doxorubicin (DXR) has been on the market for many years as an anti-cancer drug, a number of serious dose-limiting toxicities hinder its widespread use. To reduce the known toxicities of soluble DXR, various liposomes have been designed including Doxil, Caelyx, and Myocet. Myocet, a non-PEGylated liposomal formulation containing DXR, was found to reduce the toxicities associated with soluble DXR and has been used in Europe and Canada (but not the US) as a first line therapy. While regarded as successful, Myocet does have some formulation drawbacks including stability, drug release, and an arduous formulation and remote loading method for preparation. Our lab has developed a liposomal electrospray process in which formulation and remote loading occurs continuously in one step, cutting down on the total time of production and increasing the drug retention in the liposomes with respect to more conventional methods. Electrosprayed Myocet-like liposomes were then tested in vitro for release kinetics and cytotoxicity with respect to a more conventional formulation method. Myocet-like liposomes manufactured via electrospray had similar DXR loadings, hydrodynamic diameters, morphologies, and cytotoxic profiles as their thin-film hydration counterparts, but their release profiles were drastically prolonged. Our findings indicate that electrospray is a viable manufacturing procedure to scalably produce Myocet-like liposomes that appear to be more stable than those formulated through thin-film hydration.

Decomposition algorithms for synchronous flow shop problems with additional resources and setup times

In this paper, we present decomposition algorithms for synchronous flow shop problems with additional resources and setup times. In such an environment, jobs are moved from one machine to the next by an unpaced synchronous transportation system, which implies that the processing is organized in synchronized cycles. In each cycle the current jobs start at the same time on the corresponding machines and after processing have to wait until the last job is finished. Afterwards, all jobs are moved to the next machine simultaneously. During processing, each job needs one additional resource and setup times have to be taken into account when changing from one resource to another. The goal is to find a production sequence of the jobs as well as a feasible assignment of resources to the jobs such that the total production time (makespan) is minimized. We propose two decomposition strategies dealing with the two subproblems of job sequencing and resource assignment hierarchically. Both approaches are computationally evaluated and compared. As a by-product, we also present efficient heuristics for the makespan minimization problem in synchronous flow shops without setup times.

Optimizing product manufacturability in 3D printing

3D printing has become a promising technique for industry production. This paper presents a research on the manufacturability optimization of discrete products under the influence of 3D printing technology. For this, we first model the problem using a tree structure, and then formulate it as a linear integer programming, where the total production time is to be minimized with the production cost constraint. To solve the problem, a differential evolution (DE) algorithm is developed, which automatically determines whether traditional manufacturing methods or 3D printing technology should be used for each part of the production. The algorithm is further quantitatively evaluated on a synthetic dataset, compared with the exhaustive search and alternating optimization solutions. Simulation results show that the proposed algorithm can well combine the traditional manufacturing methods and 3D printing technology in production, which is helpful to attain optimized product design and process planning concerning manufacture time. Therefore, it is beneficial to provide reference of the widely application and further industrialization of the 3D printing technology.

Improved Methods to Produce Tissue-Engineered Skin Substitutes Suitable for the Permanent Closure of Full-Thickness Skin Injuries.

There is a clinical need for skin substitutes to replace full-thickness skin loss. Our group has developed a bilayered skin substitute produced from the patient's own fibroblasts and keratinocytes referred to as Self-Assembled Skin Substitute (SASS). After cell isolation and expansion, the current time required to produce SASS is 45 days. We aimed to optimize the manufacturing process to standardize the production of SASS and to reduce production time. The new approach consisted in seeding keratinocytes on a fibroblast-derived tissue sheet before its detachment from the culture plate. Four days following keratinocyte seeding, the resulting tissue was stacked on two fibroblast-derived tissue sheets and cultured at the air–liquid interface for 10 days. The resulting total production time was 31 days. An alternative method adapted to more contractile fibroblasts was also developed. It consisted in adding a peripheral frame before seeding fibroblasts in the culture plate. SASSs produced by both new methods shared similar histology, contractile behavior in vitro and in vivo evolution after grafting onto mice when compared with SASSs produced by the 45-day standard method. In conclusion, the new approach for the production of high-quality human skin substitutes should allow an earlier autologous grafting for the treatment of severely burned patients.

Comprehensive Quality Control of the ITG 68Ge/68Ga Generator and Synthesis of 68Ga-DOTATOC and 68Ga-PSMA-HBED-CC for Clinical Imaging.

A good-manufacturing-practices (GMP) (68)Ge/(68)Ga generator that uses modified dodecyl-3,4,5-trihydroxybenzoate hydrophobically bound to a octadecyl silica resin (C-18) as an adsorbent has been developed that allows for dilute HCl (0.05N) to efficiently elute metal-impurity-free (68)Ga(3+) ready for peptide labeling. We characterized the performance of this generator system over a year in conjunction with the production of (68)Ga-labeled DOTATOC and Glu-NH-CO-NH-Lys(Ahx)-HBED-CC (PSMA-HBED-CC) intended for clinical studies and established protocols for batch release. A 2,040-MBq self-shielded (68)Ge/(68)Ga generator provided metal-free (68)GaCl3 ready for peptide labeling in the fluidic labeling module after elution with 4 mL of 0.05N HCl. The compact system was readily housed in a laminar flow cabinet allowing an ISO class-5 environment. (68)Ga labeling of peptides using GMP kits was performed in 15-20 min, and the total production time was 45-50 min. Batch release quality control specifications were established to meet investigational new drug submission and institutional review board approval standards. Over a period of 12 mo, (68)Ga elution yields from the generator averaged 80% (range, 72.0%-95.1%), and (68)Ge breakthrough was less than 0.006%, initially decreasing with time to 0.001% (expressed as percentage of (68)Ge activity present in the generator at the time of elution), a unique characteristic of this generator. The radiochemical purity of both (68)Ga-DOTATOC and (68)Ga-PSMA-HBED-CC determined by high-performance liquid chromatography analysis was greater than 98%, with a minimum specific activity of 12.6 and 42 GBq/μmol, respectively. The radionuclidic ((68)Ge) impurity was 0.00001% or less (under the detection limit). Final sterile, pyrogen-free formulation was provided in physiologic saline with 5%-7% ethanol. The GMP-certified (68)Ge/(68)Ga generator system was studied for a year. The generator system is contained within the fluidic labeling module, and it is compact, self-shielded, and easy to operate using simple manual techniques. The system provides radiolabeled peptides with high (>98%) radiochemical purity and greater than 80% radiochemical yield. The (68)Ge levels in the final drug products were under the detection limits at all times. (68)Ga-DOTATOC and (68)Ga-PSMA-HBED-CC investigational radiopharmaceuticals are currently being studied clinically under investigational new drug (IND) applications submitted to the U.S. Food and Drug Administration.

Total production time minimization of a multi-pass milling process via cuckoo optimization algorithm

The milling process is a widely used conventional machining operation. Due to economic reasons, the multi-pass milling process is more convenient. However, the required time for machining increases and an optimization solution must be undertaken. In this paper, the total production time is minimized by resorting to a powerful bio-inspired algorithm, called the cuckoo optimization algorithm. The constraints are successfully handled and the optimal results are compared with those available in the literature. It is shown that the present results are better.