Processing Operations Research Articles

Problems of safe operation of saw chain sets of forest machines

Most of the volumes of timber harvesting in Russia and in developed foreign countries are produced by machine, using sorting technology. At the same time, in most cases, either harvesters (producing sorting in apiaries) or felling-packing machines and processors (producing sorting in the upper warehouse) are used to perform processing operations. The vast majority of these machines are equipped with saw chain headsets, the correctness of maintenance and operation of which directly affects not only the effectiveness of basic logging operations, but also the safety of their performance. The article discusses the basic rules of safe operation and proper maintenance of saw sets of forest machines.

The Effect of Processing Operations on the Polyphenol Content of Cocoa Beans: A Review

The Effect of Processing Operations on the Polyphenol Content of Cocoa Beans: A Review

Automatic Marker Generation to Similarity Based Region Merging Algorithm using Edge Information

One of the most important tasks in computer vision is image segmentation. Several interactive strategies are utilized for picture segmentation because automated techniques are difficult for this kind of work. The outcome of interactive methods is mostly determined by user input. Obtaining excellent interactions for huge datasets is challenging. However, automated picture segmentation is starting to play a significant role in image analysis and computer vision. Effective and efficient segmentation outcomes are obtained using the interacting region merging method suggested by Maximal Similarity based region merging algorithm. Limitation of MSBRM is it requires some efforts on the part of users and is yet not a fully-automatic approach. Here, we suggest a completely fresh unsupervised image segmentation method that combines edge information with MSBRM. We propose an integrated framework to generate object markers for similarity based region algorithm using edge information. Long edges give rough distribution of objects in image. After retrieving edges using phase congruency, edge processing operations are employed to remove small edges and to group color similar long boundaries. Centroids of long boundaries are used as object markers to the MSBRM algorithm. The generation of object markers is done using edge segment grouping. These object markers guide the region merging process. The proposed method shows its effectiveness in segmenting natural real world color images.

Fission counter array for pulse-mode measurements of high-flux and high-energy neutrons

This manuscript describes a neutron counting system based on cylindrical fission counters that can monitor neutron activity for high-energy neutron flux above 10 MeV under electrically noisy environments with intense gamma rays. Miniature fission counters with depleted uranium as sensitive material and modular electronics were built for digital signal processing and high-countrate operation. The counters are 9.5 mm in diameter and 71.1 mm in active length. The author presents the results of Monte Carlo simulations of the fission-counter response for selected neutron sources and energies based on ENDF7.1, JENDL-5, and TENDL-2021 nuclear data libraries from 1 meV to 200 MeV. For a white neutron beam (E‾ = 16.36 MeV) that irradiates the front face of a counter, the intrinsic efficiency is evaluated to be (2.24 ± 0.02) × 10−5 counts/n, while the efficiency of the counter in the array appears to increase by at most 6.7%.

Properties of processing and data acquisition methods in test methods of chemical analysis

Chemical analysis is a crucial source of information for assessing the state of the environment, evaluating the human body condition, and serving as a diagnostic tool for detecting diseases and more. The use of simple, rapid, and cost-effective analysis methods without the need for specialized laboratory conditions and personnel with specific qualifications, such as test methods, contributes to the effective implementation of well-known techniques for analyzing the chemical composition of environmental objects and for use in the field of healthcare. Scanner indication of the analytical signal in chemical analysis is an objective, fast, and automated method for assessing the color characteristics of colored samples. The use of scanner indication in obtaining the analytical signal eliminates errors associated with subjective evaluation and assists individuals with color vision impairments, speeding up data collection and processing operations. Considering and controlling the light source in scanning systems is crucial to ensuring the stability and accuracy of obtained images under different lighting conditions. To obtain the analytical signal, it is primarily necessary to process the image to obtain the region of interest, which is determined by segmentation, manual methods, and using image processing techniques. The analysis of obtained values is carried out by constructing a linear or nonlinear relationship of color values in the selected color model converted to a single value of the analytical signal to concentration. Most existing systems for scanner detection of the analytical signal in analytical test methods require human involvement in obtaining and interpreting results, limiting the application areas of these methods of analytical signal indication. Further research is focused on creating a reliable method for obtaining the analytical signal using a smartphone camera based on image processing techniques, allowing for the automation of obtaining, processing, and improving the reproducibility of results in chemical test analyses.

Design and Construction of a Rapid Milk Chiller Using Cold Energy Storage System in the Context of Bangladesh

Milk is a highly sensitive product that must be collected and cooled within a few hours to reduce losses due to chemical spoilage and to preserve quality. As milk production is often remote from markets and processing facilities, milk chillers using thermal energy storage (TES) units provide the means for preserving quality through chilling during a power cut and hygienic storage before onward transportation to processing facilities and operation of the chiller at maximum thermal efficiency. This study gives an overview of thermal energy storage (TES) base rapid milk chiller. A review of TES for cold storage applications utilizing solid-liquid phase change materials has been done. Various perspectives were focused on the different stages of the work: phase change materials (PCMs), exemplification, improvement in exchange of heat, and the impact of the whole process on the quality of the milk Materials used as potential PCMs by specialists at low temperatures (less than 4 °C) are condensed and a portion of their thermo-physical properties are accounted for. The concept of planning and measuring procedures based on the determined load profile for structure day is introduced. In this design of a milk chilling unit using thermal energy storage, two cycles have been combined to get the desired cooling temperature. One is the vapor compression cycle, which can also be called the ice storage cycle. Another one is the milk chilling cycle. The main purpose of the milk chilling cycle is to keep the milk temperature between 2°C to 4°C. The comparison of using cold water with ethylene glycol (PCM) as a storage source of refrigeration for the milk cooling process based on the compressor capacity, ice storage box volume, and power consumed at the variable of cooling load is presented. Also, the effect of using cold storage to reduce the refrigeration capacity and energy saving is presented. The time duration of the milk chiller’s capacity to keep a specific amount (20 liters) of milk cool has been calculated to determine the variance and efficiency of the system compared to other milk chilling processes. Some suggestions concerning the planning of milk chiller hardware are given. Unique consideration was paid to the examination of explicit highlights of heat transfer phenomena in ice storage boxes including the appraisal of the length and the rate of ice arrangement and dissolution. The approach of estimating parts of the ice storage capacity framework incorporated into the milk chilling framework arranged in hot, wet, and dry atmospheres is exhibited. In light of the hourly cooling burden figuring that was completed utilizing Carrier’s Hourly Analysis Program, estimating the ice thermal capacity framework for various working procedures including full, chiller priority, and ice priority storage tasks for the design are displayed. At last, an examination of some operational qualities of the framework is broken down.

Recent University Research, Implementation and Education in Support of Pyrometallurgical Lead Processing

The increasing chemical complexity of lead process streams encountered in industrial high temperature processing operations, as the result of declining primary resources, increased metal recycling and increased overall range of metals in modern devices has highlighted the urgent need for new predictive tools, fundamental phase equilibria and thermodynamic information and thermodynamic models to characterise the chemical behaviour of these systems. The paper examines recent progress in experimental and thermodynamic modelling research on process fundamentals, the availability of advanced, predictive computer-based tools and the implementation of the research outcomes into industrial practice. A wide range of chemical systems and phase assemblages have been studied. Some examples are taken from the current research program at PYROSEARCH, which involves the characterisation of multi-component, multi-phase gas-slag-matte-speiss-metal-solids systems with the PbO-ZnO-“Cu2O”-FeO-Fe2O3-CaO-Al2O3-MgO-SiO2-S as major and As-Sn-Sb-Bi-Ag-Au-Ni-Co-Cr-Na as minor elements with focus on systems directly relevant to lead primary and recycling pyrometallurgical processes. Examples of the application of advanced analytical techniques to fundamental and applied industrial research are also given. The implementation of new research outcomes into industrial practice depends critically on commitments by research staff as well as industry management and the availability of well-trained metallurgical engineers. We examine the current status of research implementation, university research, metallurgical engineering education and the availability of suitable educational pathways and initiatives that can be taken to increase undergraduate enrolments. Active engagement and support by industry is critical in ensuring the continuation of academic programs and advanced technical skills required by the industry.

Development of Customized MIPS_32 Core Processor for Image Processing Applications

Definitely, image processing operations without advanced and expensive microprocessors consume more time, power, and larger programs. So, improving the reasonable cost of microprocessors is crucial in this situation. This paper proposes an improvement for the MIPS_32 architecture that is called a Customized MIPS_32 (CMIPS_32) to enhance the capabilities of image processing (IP) operations. The proposal aims to increase throughput by minimizing the iterative fetching of instructions required by a certain IP operation into a single customized IP instruction. The architecture of MIPS_32 was developed in two phases. Firstly, the Register File, control unit, and ALU are modified to manipulate the information related to the IP operations. Secondly, two new units, the address calculation unit and the last pixel detection unit, were proposed to determine a certain image's starting and ending addresses. Furthermore, the MIPS_32 pipeline is customized to have five to six stages depending on the intensity of operation required by a certain IP instruction to decrease the number of machine clocks and the power consumed. The proposal was implemented using the Zed-Board XC7Z020CLG484-1 FPGA. The results showed that the computation speedup increased by a factor equal to the number of standard instructions required to execute the same operation performed by one of the proposed IP instructions. The CMIPS_32 consumed less power than other models that were implemented on Spartan3-XC3S1500L, Virtex5-XC5VFX30T, Virtex6-XC6VLX75T, and Virtex6-Low-Power-XC6VLX75T by 0.0138W, 0.6468W, 1.31W, and 0.7898W, respectively. Comparing the power consumed by the proposal with the GPU proved that the CMIPS_32 consumes less than the NVIDIA-GPU-GTX980 by 63.8698W. Index Terms— FPGA, Image processing instructions, MIPS_32, Verilog.

Edge Detection Model Performance Using Canny, Prewitt and Sobel in Face Detection

Detection of objects in the form of objects, humans and other objects at this time has been widely applied in many aspects of life. The help of this technology can facilitate human work, one of which is facial detection to get information about a person's identity. Face identification and detection is closely related to Data Mining science with Image Processing sub-science. This facial detection and recognition can use several technical approaches, one of which is to use edge detection. Edge detection is one of the basic operations of image processing. In the image classification process, edge detection is required before image segmentation processing. There are several methods that can be used to perform edge detection such as Canny, Prewitt and Sobel. These three methods are methods that have accurate and good detection results, with the advantages of each method having its own added value. From the results of previous studies that stated these three methods have good results, it became interesting to conduct a comparative study of these three methods in detecting edges in facial images. Edge detection applied to this study identifies facial images, and will get similarities with the original image from the result analysis process, and is reinforced by measurement results using the Mean Square Error error degree. The final result of this study states that this study the most optimal Mean Square Error measurement results obtained the final results in the Canny method of 10, the Prewitt method of 41 and Sobel of 29. These results show that the value of the Canny method has the smallest Mean Square Error value, which indicates that the Canny method on facial image edge detection has the most optimal results.

Fragmentation energy calculation model of coal crushed by impact load

ABSTRACT Rock fragmentation is a common physical and mechanical phenomenon that exists in a variety of ranges from the mining and processing. Communication is an important operation in coal processing whereby the coal block coming from coalmines is crushed into fragmentations with reduced size, which accounts for 80% of the electricity consumption of mineral processing circuits. Fragmentation energy, which is related to the coal particle size distribution, is an essential parameter for improving the efficiency of shearer, road-header, and crusher. Coal particles are generally simplified into fine or near spherical shapes for analytical and numerical simulation purposes. This research aims to establish the fragmentation energy calculation model for coal fragmentations with coarse and wide size distribution based on the analysis of size distribution and energy-size relationships of coal particles. It has been demonstrated by the results that the fragmentation energy of impact load crushed coal can be determined based on Rittinger’s theory with fractal or RR model particle size distribution.

Processing of a Part Such as a Composite Bearing Housing on a Milling Machine With a Digital Control Program

In the era of the industrial revolution of ndustry 4.0, the Republic of Kazakhstan is rapidly introducing automated robots and digital control programs in many of its production facilities. In this context, special attention is paid to modern technologies, and AKIRA SEIKI milling machines with FANUC control software stand out as advanced technologies in this process. They are becoming the most popular in the CIS countries due to the economic efficiency and intellectual support of the Taiwanese manufacturer. Practical aspects of constructing CNC milling machines and their practical use are presented in this article. Particular attention is paid to the functionality of milling machines using the example of processing such a part as a composite bearing housing. In addition, the process of writing processing operation codes in the CIMKO computer program is described. The code is provided with brief descriptions to help you understand the compiled workpiece processing operations. With the growing need for efficiency and precision in production, many companies and industrial plants in the Republic of Kazakhstan are considering AKIRA SEIKI milling machines with FANUC control software as a major investment. These machines not only provide high productivity, but also help automate complex technological processes. CIMKO, among other things, allows the development and optimization of machining code, which complements the efficiency and accuracy of the machines.

Economic Analysis of Cost and Returns in Turmeric Production and Processing in the Chamarajanagar District of Karnataka, India

This study investigated the economic dynamics of turmeric production and primary processing in Chamarajanagar district, Karnataka, emphasized the significant role of this region in enhancing India's reputation for producing high-curcumin-content turmeric. Despite the growing domestic and international markets for turmeric, which have contributed to the crop's substantial increase in production and productivity over recent decades, there remains a significant gap in organized processing units at the local level. The analysis employed different cost concepts and the Garrett Ranking Technique. By examining the economic aspects of both turmeric cultivation and primary processing phases among farmers in the district, the findings revealed that farmers accrue a net return of ₹18,134 per acre from cultivation after incurring costs of ₹86,424, and a higher net return of ₹24,775 per acre from primary processing with an incurred cost of ₹99,439 per acre. The cost-benefit analysis further underscores the economic viability of turmeric cultivation, with ratios of 1.21 without primary processing and 1.25 with it, thereby highlighting the substantial profitability of turmeric production for local growers. However, the study identifies significant challenges, such as labour shortages and elevated wage rates, attributed to the crop's labour-intensive nature. Moreover, while primary processing increases profitability, it also demands considerable labour and time, potentially compromising the quality of turmeric powder. The research suggests that the adoption of advanced technologies and machinery in curing and processing operations could mitigate these challenges, enhancing efficiency and product quality in turmeric cultivation and processing sectors.

AN INVESTIGATION ON SANITARY AND HYGIENE PRACTICES AT THE GBAGI COMMUNITY SLAUGHTERHOUSE, IBADAN, SOUTHWEST NIGERIA.

The sanitary conditions of a food processing facility play a vital role in the safety and quality of its final products. This study assessed the hygiene practices and sanitary conditions of the Gbagi Community Slaughterhouse in Ibadan, Nigeria, to identify the factors hindering sanitation and meat hygiene at the facility, and provide recommendations for improvement. The study was conducted using a combination of observation and surveys as the data collection technique. The activities taking place in the slaughterhouse were observed for two weeks during which certain practices were documented textually and pictorially. Twelve key informants comprising butchers, cleaners, buyers, and people in the neighborhood were purposively recruited as study participants and were interviewed, using open-ended questions about the sanitation and hygiene practices at the facility. All obtained data were analyzed qualitatively by thematic content analysis. Study results showed poor waste management practices, inadequate ante- and post-mortem veterinary inspection of slaughtered animals, the absence of requisite slaughterhouse infrastructure, and the unhygienic behaviors of slaughterhouse personnel. The sanitary and hygiene practices of the Gbagi Community Slaughterhouse environment fall below the required standards for food processing operations and hence, poses a risk to food safety and public health. An integrated involvement of relevant arms of government is needed at the state and local levels for sanitary enforcement, provision of critical waste management infrastructure at the Gbagi slaughterhouse, and education of slaughterhouse personnel, so as to prevent microbial food contamination and safeguard public health.

Influence of N,N′‐ethylene bis oleamide on the flowability of the acrylonitrile‐butadiene‐styrene resin and lubrication mechanism

AbstractAs a high‐performance engineering plastic, the acrylonitrile‐butadiene‐styrene (ABS) resin possesses excellent heat resistance, chemical resistance, and toughness. However, there is a lack of flow properties of the ABS resin for many processing operations. With the aim of enhancing the flowability of the ABS resin, the effect of N,N′‐ethylene bis oleamide (EBO) as a new lubricant on the melt flow rate (MFR), torque value, and rheological behavior of the ABS resin was investigated. The result showed the MFR of the ABS resin with 2.0 wt% EBO was 22.1 g/10 min, which was improved by 49% compared with the pure ABS resin (14.8 g/10 min). The torque value of the ABS resin, including 2.0 wt% EBO (1.69 N m) was lower than that of the pure ABS resin (2.03 N m). The rheological study further indicated that EBO can reduce the complex viscosity of the ABS resin. The above results indicated that EBO was an effective lubricant for the ABS resin. A possible lubrication mechanism was proposed based on the consequences of the rotational rheometry, dynamic mechanical analysis, and molecular dynamics simulation. EBO decreased the entanglement density of the polystyrene‐acrylonitrile (SAN) molecular chains and increased the mobility of the SAN molecular chain segments. On the other hand, EBO increased the free space of motion of the SAN molecular chain segments due to the free‐volume effect thereby increasing the mean square displacement of the system. This work will provide a new way to achieve the high‐flow ABS resin and provide new insights into the lubrication mechanism of lubricants in the ABS resin thereby expanding the applications of the ABS resin.

Characterizing low-grade refractory gold ores using automated mineralogy coupled with LA ICP-MS

Researchers have made notable progress in quantifying refractory components causing gold losses in traditional extraction methods. The potential for improving gold recoveries lies in targeted re-treatment of the 'invisible' gold fraction hosted within various ore minerals, even at low concentrations. This study presents a methodology for analysing the refractory components that cause gold losses in traditional extraction methods. The approach utilizes automated mineralogical techniques in conjunction with in-situ laser ablation inductively coupled plasma mass spectrometry (LA ICP-MS) to characterize low-grade refractory ores and assess gold deportment. The methodology combines pre-concentration gravity separation, traditional chemical and mineral techniques, and LA ICP-MS to generate comprehensive datasets. To demonstrate the practical application of the methodology, a case study was conducted on historical tailings material from Witwatersrand's Evander Goldfield in South Africa. The case study aimed to determine the mineralogical distribution of gold that cannot be extracted through cyanidation. The results indicated that invisible gold is primarily hosted in pyrite (with an average concentration of 10.21 ppm representing 32 % of total gold), other sulphides (with an average concentration of 1.29 ppm representing 0.42 % of total gold), and oxides (with an average concentration of 0.50 ppm representing 1 % of total gold). The remaining gold is present in discrete fine cyanide amenable phases (with 28 % deportment) and silicate-hosted phases (with 39 % deportment). Environmental monitoring of the Witwatersrand tailings material revealed a net “acid-producing” nature, with high concentrations of heavy metals (such as As, Cu, Pb, Mn, Hg, and Ni) associated with sulphides (with over 78 % deportment). The deportment information obtained through this approach can optimize ore processing strategies and provide valuable insights for future remediation plans. By characterizing the refractory components causing gold losses and understanding the distribution of gold within the ore, this methodology offers the potential to enhance gold recovery and improve the efficiency of ore processing operations.

Lateral heterostructures of WS2 and MoS2 monolayers for photo-synaptic transistor

Von Neumann architecture-based computing, while widely successful in personal computers and embedded systems, faces inherent challenges including the von Neumann bottleneck, particularly amidst the ongoing surge of data-intensive tasks. Neuromorphic computing, designed to integrate arithmetic, logic, and memory operations, has emerged as a promising solution for improving energy efficiency and performance. This approach requires the construction of an artificial synaptic device that can simultaneously perform signal processing, learning, and memory operations. We present a photo-synaptic device with 32 analog multi-states by exploiting field-effect transistors based on the lateral heterostructures of two-dimensional (2D) WS2 and MoS2 monolayers, formed through a two-step metal–organic chemical vapor deposition process. These lateral heterostructures offer high photoresponsivity and enhanced efficiency of charge trapping at the interface between the heterostructures and SiO2 due to the presence of the WS2 monolayer with large trap densities. As a result, it enables the photo-synaptic transistor to implement synaptic behaviors of long-term plasticity and high recognition accuracy. To confirm the feasibility of the photo-synapse, we investigated its synaptic characteristics under optical and electrical stimuli, including the retention of excitatory post-synaptic currents, potentiation, habituation, nonlinearity factor, and paired-pulse facilitation. Our findings suggest the potential of versatile 2D material-synapse with a high density of device integration.

Multilevel Ferroelectric Domain Wall Memory for Neuromorphic Computing

AbstractLow‐power and parallel processing Neuromorphic computing that imitates on the human brain's extraordinary data processing and learning capabilities is promising in non‐von Neumann application platforms in the post‐Moore era. Ferroelectric domain walls appearing as nanoscale topological defects in solids exhibit coexisting ordering parameters besides the spontaneous polarization, leading to the emergence of rich physics and electronic effects in the development of neuromorphic electronics that go beyond the conventional CMOS. In this study, the four‐state domain wall memory is developed on LiNbO3 ferroelectric thin films integrated with Si substrates, where each state can be stably manipulated at a specific low voltage, showcasing outstanding fatigue resistance and retention performance. The constructed crossbar array that functions as a kernel for image convolution can be used to implement processing operations like image filtering, sharpness enhancement, and edge detection. Additional simulation from a convolutional neural network model shows 96.98% accuracy on the Modified National Institute of Standards and Technology handwritten digits dataset. The stable multi‐state domain wall memory provides a new approach for computing and promotes research in domain wall electronics to meet future enormous demands of big data.

Sensitive organic/inorganic polarized photodetectors enhanced by charge transfer with image sensing capacity.

Organic photodetectors (OPDs) have attracted increasing attention in the future wearable sensing and real-time health monitoring, due to their intrinsic features including the mechanical flexibility, low-cost processing and cooling-free operations; while their performances are lagging as the results of inferior carrier mobility and small exciton diffusion coefficient of organic molecules. Graphene exhibits the great photoresponse with wide spectral bandwidth and high response speed. However, weak light absorption and the absence of a gain mechanism have limited its photoresponsivity. Here, we report a sensitive organic/inorganic phototransistor with fast response speed by coupling PTCDA organic single crystal with the monolayer graphene. The long range exciton diffusion in highly ordered π-conjugated molecules, efficient exciton dissociation and charge transfer at the PTCDA/graphene heterointerfaces, and the high mobility of graphene enable a high responsivity (8 × 104A/W), short response time (220 µs) and excellent specific detectivity (>1011 Jones), which is higher than the level of commercial on-chip device. This interfacial photogating effect is verified by the high-resolution spatial photocurrent mapping experiment. In addition, the high sensitivity to polarization is clear and the ultrahigh photoconductive gain enables a near-infrared (NIR) response for 980 and 1550 nm. Finally, high-speed visible and NIR imaging applications are successfully demonstrated. This work suggests that high quality organic single crystal/graphene is a promising platform for future high performance optoelectronic systems and imaging applications.

The Sweet Revolution: Sustainable Development of Honey Sector in Rajasthan, India- a Value Chain Based Approach

The primary objective to undertake this current study is to examine the Honey sector, specifically in the Rajasthan region of India. In particular, a value chain based approach is utilized to understand the existing challenges and prospects of the sector. In addition, the study aims to provide recommendations to strengthen the production, distribution, and sustainable development of Honey sector. India, being an agro economy, agriculture and allied activities constitute a substantial chunk of India’s GDP. Rajasthan, the largest state in terms of area in India, is well-known because of its abundant biodiversity and is acknowledged as the top crop producer, accounting for an estimated 50% of the country's supply of seed spices. Drawing from the body of existing literature, this study demonstrates how the Indian honey industry has not been able to live up to its potential and instead has fallen short of expectations. These factors include a lack of technological adoption, access to markets, and value chain development. A lack of governmental support, a lack of systematic marketing and distribution strategies, a lack of knowledge about beekeeping, limited access to sophisticated tools and technology integration, and a lack of chemicals required for efficient beekeeping and honey processing operations are the main obstacles impeding the rapid development of the honey's consumption industry. The primary approaches envisioned for the long-term growth of the honey industry should include effective methods of delivering components, knowledge-based methods of processing honey from bees, integration of processes that add value, and creation of market connections for local farmers, beekeepers, and honey producers. As a result, honey producers make more money while supporting the industry's participants' performance, profitability, and sustainable way of life. The findings of this study provide policymakers and government agencies with ideas on how to create programs for the long-term growth of Rajasthan’s honey sector.

Coordinating scheduling and rejection decisions in a two-machine flow shop scheduling problem

We study a two-machine flow shop scheduling problem where any operation can be rejected at a certain cost. A solution for such a problem requires two sets of decisions. The first involves the partition of the set of operations into two subsets: the set of operations that are accepted for scheduling in the shop, and the set of rejected operations. The second decision involves scheduling the set of accepted operations in the shop. The objective is to find a solution that minimizes the sum of the makespan and the total rejection cost. We prove that the problem is NP-hard even if all processing operations have identical processing times and identical rejection costs on either one of the two machines. We show, however, that the problem is fixed parameterized tractable with respect to a parameter that combine the number of different processing times on both machines with the number of different rejection costs on one out of the two machines. We also provide a pseudo-polynomial time algorithm for the problem, which we then convert into a fully polynomial time approximation scheme. This is achieved by dividing the problem into a set of subproblems and deriving a fully polynomial time approximation scheme for each one of them, separately. Finally, we present an integer linear programming formulation of the problem and two simple 2-approximation algorithms.