International Journal of Membrane Science and Technology
The concept of statistics-based control is nearly a century old. The basic assumption is that the... more The concept of statistics-based control is nearly a century old. The basic assumption is that the measurement is precise and therefore all calculation based on these data is also precise. Typically, this assumption is not far from reality and thus does not affect the proposed control limits. However, in some cases the rounding-off of measurements may lead to erroneous decisions. This study examines the effects of rounding-off on the average (X ?) control lines and suggests a simple method way to design new control lines, based on the conventional average run length (ARL).
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
International Journal of Production Research, Dec 1, 1997
The problem of scheduling activities in a project to maximize its net present value (NPV) has bee... more The problem of scheduling activities in a project to maximize its net present value (NPV) has been solved recently for the case where net cash flow magnitudes are dependent on the time of realization. In this problem, incentive payments and penalties for early and late event occurrences respectively, as well as the cost of resources over time, are time dependent. We present a branch and bound solution approach for this problem. We compare the NPVs of the solutions obtained from the branch and bound algorithm with those of a simulated annealing approach developed earlier. Our computational results show that the branch and bound approach outperforms the best known simulated annealing implementation.
This paper proposes a new technique for assisting search technique optimizers (most evolutionary,... more This paper proposes a new technique for assisting search technique optimizers (most evolutionary, swarm, and bio-mimicry algorithms) to get an informed decision about terminating the heuristic search process. Current termination/stopping criteria are based on predetermined thresholds that cannot guarantee the quality of the achieved solution or its proximity to the optimum. So, deciding when to stop is more an art than a science. This paper provides a statistical-based methodology to balance the risk of omitting a better solution and the expected computing effort. This methodology not only provides the strong science-based decision making but could also serve as a general tool to be embedded in various single-solution and population-based meta-heuristic studies and provide a cornerstone for further research aiming to provide better search terminating point criteria.
Measurements can often be imprecise and subjected to rounding-off. Typically, this rounding-off i... more Measurements can often be imprecise and subjected to rounding-off. Typically, this rounding-off is ignored and assumed to have little to no effect. However, when the measuring scale step is not negligible, it may affect statistical control tools such as X-chart. Designing statistical process controls without considering the effects of rounding leads to high exposure to false negative results. This study illustrates the effects of rounding on the X-chart and shows that the result may further deteriorate due to asymmetry (incompatibility of the process and the measuring device parameters). A new simple method to design control limits is proposed, based on maintaining the original characteristics of the chart as devised by Shewhart.
International Journal of Production Research, Nov 23, 2017
This paper presents a novel technique for improving the runtime of metaheuristic search optimisat... more This paper presents a novel technique for improving the runtime of metaheuristic search optimisations. The technique was applied on a new practical problem: several-release-problem (SRP) that characterises the modern industry. Many modern products are replaced by their next version due to incessant R&D activity, resulting in a short marketable life length. There are numerous such examples including the automotive industry, electronic devices and software products. These intermediate releases enable organisations to maximise their value for a given investment. The challenge faced by the industry is to decide which features to include in which version. The paper proves that SRP is NP-hard, thus cannot be solved practically using analytical approaches. A near-optimal, simple technique for determining the feature content of all version releases of the planning horizon is presented. The innovative approach utilises techniques adopted from the clustering domain to enhance the optimisation. The clustering enables skipping significant amounts of unattractive zones of the space. Verification and validation of the proposed technique are presented. The paper compares different heuristics and the shows that embedding the suggested clustering into general methods, yields significantly shorter runtime, and improves the solution’s quality. The enhancement technique can be applied to other combinatorial problems and metaheuristics.
European Journal of Operational Research, Jun 1, 2017
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service... more This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Highlights We introduce a new practical problem optimizing version release dates and their feature contents. We define a novel optimization model for adequately setting: release contents and release dates. We offer a benchmark set of these new problems and their solutions for further research. We validated our results against greedy heuristics and provided the results.
International journal of adolescence and youth, Aug 27, 2019
Although choosing between several alternatives is the basic and most common process of decision-m... more Although choosing between several alternatives is the basic and most common process of decision-making, it has been well established that when having to decide, people are prone to various biases and seldom elect an alternative rationally. One of the most common and wellresearched biases is the 'choice-bias' and many researches demonstrated its effect on decision-makers (both high-level and daily decisions) of the previous generations. This research examined the hypothesis that since the psychological development of 'generation Y' differs significantly from the researched generations, youth today are more resistant to this specific bias. A lifetime of constant exposure to the overabundance of suggestions and opportunities may have influenced decision-making capabilities. A study conducted on two separate groups of students (256 participants) revealed that no choice bias was observed, unlike similar studies conducted with previous generation populations.
Research in educational administration & leadership, May 7, 2020
Article Info Smartphone applications have become increasingly popular, influencing functioning in... more Article Info Smartphone applications have become increasingly popular, influencing functioning in all life domains. This study investigated the influence of the WhatsApp application on decision-making processes among kindergarten-managers. The research aimed to investigate the types of decisions made using WhatsApp. To examine this, a 3-phase mixed-method research was applied: (1) 23 semi-structured interviews with kindergarten managers. (2) Analysis of 74 WhatsApp managers-parents conversations. (3) A questionnaire administered to 324 kindergarten-managers. The managers reported a constant pressure for an immediate reaction and rapid decision making. Despite the pressure, managers claim they can limit the decision making to simple decisions and postpone complex decision making to off-line procedures. Yet, analysis of the questionnaire results indicate that this claimed ability to differentiate and limit the decision making to simple ones, is not the general case: managers who benefitted more from WhatsApp tended to broaden the decision-making scope to all types of decisions. The expectation is that, as WhatsApp benefits to managers
Measurements can often be imprecise and subjected to rounding-off. Typically, this rounding-off
... more Measurements can often be imprecise and subjected to rounding-off. Typically, this rounding-off
is ignored and assumed to have little to no effect. However, when the measuring scale step is not
negligible, it may affect statistical control tools such as X-chart. Designing statistical process
controls without considering the effects of rounding leads to high exposure to false negative results. This study illustrates the effects of rounding on the X-chart and shows that the result may
further deteriorate due to asymmetry (incompatibility of the process and the measuring device
parameters). A new simple method to design control limits is proposed, based on maintaining the
original characteristics of the chart as devised by Shewhart.
... 2. Generate a random value 0+ or 0 3. If ti = gi, let ti tj + 0+ 4. If ti = Li, let ti ti 0 5... more ... 2. Generate a random value 0+ or 0 3. If ti = gi, let ti tj + 0+ 4. If ti = Li, let ti ti 0 5. Otherwise let ti ti + 0+ or ti ti O with the same probability. ... All three strategies were tested on a set of ran domly generated problems as discussed next. ...
The process of project portfolio selection is crucial in many organizations, especially R&D organ... more The process of project portfolio selection is crucial in many organizations, especially R&D organizations. There is a need to make informed decisions on the investment in various projects or lack thereof. As the projects may continue over more than 1 year, and as there are connections between various projects, there is a need to not only decide which project to invest in but also when to invest. Since future benefits from projects are to be depreciated in comparison with near-future ones, and due to the interdependency among projects, the question of allocating the limited resources becomes quite complex. This research provides a novel heuristic method for allocating the limited resources over multi-annual planning horizons and examines its results in comparison with an exact branch and bound solution and various heuristic ones. This paper culminates with an efficient tool that can provide both practical and academic benefits.
International Journal of Membrane Science and Technology
The concept of statistics-based control is nearly a century old. The basic assumption is that the... more The concept of statistics-based control is nearly a century old. The basic assumption is that the measurement is precise and therefore all calculation based on these data is also precise. Typically, this assumption is not far from reality and thus does not affect the proposed control limits. However, in some cases the rounding-off of measurements may lead to erroneous decisions. This study examines the effects of rounding-off on the average (X ?) control lines and suggests a simple method way to design new control lines, based on the conventional average run length (ARL).
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
International Journal of Production Research, Dec 1, 1997
The problem of scheduling activities in a project to maximize its net present value (NPV) has bee... more The problem of scheduling activities in a project to maximize its net present value (NPV) has been solved recently for the case where net cash flow magnitudes are dependent on the time of realization. In this problem, incentive payments and penalties for early and late event occurrences respectively, as well as the cost of resources over time, are time dependent. We present a branch and bound solution approach for this problem. We compare the NPVs of the solutions obtained from the branch and bound algorithm with those of a simulated annealing approach developed earlier. Our computational results show that the branch and bound approach outperforms the best known simulated annealing implementation.
This paper proposes a new technique for assisting search technique optimizers (most evolutionary,... more This paper proposes a new technique for assisting search technique optimizers (most evolutionary, swarm, and bio-mimicry algorithms) to get an informed decision about terminating the heuristic search process. Current termination/stopping criteria are based on predetermined thresholds that cannot guarantee the quality of the achieved solution or its proximity to the optimum. So, deciding when to stop is more an art than a science. This paper provides a statistical-based methodology to balance the risk of omitting a better solution and the expected computing effort. This methodology not only provides the strong science-based decision making but could also serve as a general tool to be embedded in various single-solution and population-based meta-heuristic studies and provide a cornerstone for further research aiming to provide better search terminating point criteria.
Measurements can often be imprecise and subjected to rounding-off. Typically, this rounding-off i... more Measurements can often be imprecise and subjected to rounding-off. Typically, this rounding-off is ignored and assumed to have little to no effect. However, when the measuring scale step is not negligible, it may affect statistical control tools such as X-chart. Designing statistical process controls without considering the effects of rounding leads to high exposure to false negative results. This study illustrates the effects of rounding on the X-chart and shows that the result may further deteriorate due to asymmetry (incompatibility of the process and the measuring device parameters). A new simple method to design control limits is proposed, based on maintaining the original characteristics of the chart as devised by Shewhart.
International Journal of Production Research, Nov 23, 2017
This paper presents a novel technique for improving the runtime of metaheuristic search optimisat... more This paper presents a novel technique for improving the runtime of metaheuristic search optimisations. The technique was applied on a new practical problem: several-release-problem (SRP) that characterises the modern industry. Many modern products are replaced by their next version due to incessant R&D activity, resulting in a short marketable life length. There are numerous such examples including the automotive industry, electronic devices and software products. These intermediate releases enable organisations to maximise their value for a given investment. The challenge faced by the industry is to decide which features to include in which version. The paper proves that SRP is NP-hard, thus cannot be solved practically using analytical approaches. A near-optimal, simple technique for determining the feature content of all version releases of the planning horizon is presented. The innovative approach utilises techniques adopted from the clustering domain to enhance the optimisation. The clustering enables skipping significant amounts of unattractive zones of the space. Verification and validation of the proposed technique are presented. The paper compares different heuristics and the shows that embedding the suggested clustering into general methods, yields significantly shorter runtime, and improves the solution’s quality. The enhancement technique can be applied to other combinatorial problems and metaheuristics.
European Journal of Operational Research, Jun 1, 2017
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service... more This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Highlights We introduce a new practical problem optimizing version release dates and their feature contents. We define a novel optimization model for adequately setting: release contents and release dates. We offer a benchmark set of these new problems and their solutions for further research. We validated our results against greedy heuristics and provided the results.
International journal of adolescence and youth, Aug 27, 2019
Although choosing between several alternatives is the basic and most common process of decision-m... more Although choosing between several alternatives is the basic and most common process of decision-making, it has been well established that when having to decide, people are prone to various biases and seldom elect an alternative rationally. One of the most common and wellresearched biases is the 'choice-bias' and many researches demonstrated its effect on decision-makers (both high-level and daily decisions) of the previous generations. This research examined the hypothesis that since the psychological development of 'generation Y' differs significantly from the researched generations, youth today are more resistant to this specific bias. A lifetime of constant exposure to the overabundance of suggestions and opportunities may have influenced decision-making capabilities. A study conducted on two separate groups of students (256 participants) revealed that no choice bias was observed, unlike similar studies conducted with previous generation populations.
Research in educational administration & leadership, May 7, 2020
Article Info Smartphone applications have become increasingly popular, influencing functioning in... more Article Info Smartphone applications have become increasingly popular, influencing functioning in all life domains. This study investigated the influence of the WhatsApp application on decision-making processes among kindergarten-managers. The research aimed to investigate the types of decisions made using WhatsApp. To examine this, a 3-phase mixed-method research was applied: (1) 23 semi-structured interviews with kindergarten managers. (2) Analysis of 74 WhatsApp managers-parents conversations. (3) A questionnaire administered to 324 kindergarten-managers. The managers reported a constant pressure for an immediate reaction and rapid decision making. Despite the pressure, managers claim they can limit the decision making to simple decisions and postpone complex decision making to off-line procedures. Yet, analysis of the questionnaire results indicate that this claimed ability to differentiate and limit the decision making to simple ones, is not the general case: managers who benefitted more from WhatsApp tended to broaden the decision-making scope to all types of decisions. The expectation is that, as WhatsApp benefits to managers
Measurements can often be imprecise and subjected to rounding-off. Typically, this rounding-off
... more Measurements can often be imprecise and subjected to rounding-off. Typically, this rounding-off
is ignored and assumed to have little to no effect. However, when the measuring scale step is not
negligible, it may affect statistical control tools such as X-chart. Designing statistical process
controls without considering the effects of rounding leads to high exposure to false negative results. This study illustrates the effects of rounding on the X-chart and shows that the result may
further deteriorate due to asymmetry (incompatibility of the process and the measuring device
parameters). A new simple method to design control limits is proposed, based on maintaining the
original characteristics of the chart as devised by Shewhart.
... 2. Generate a random value 0+ or 0 3. If ti = gi, let ti tj + 0+ 4. If ti = Li, let ti ti 0 5... more ... 2. Generate a random value 0+ or 0 3. If ti = gi, let ti tj + 0+ 4. If ti = Li, let ti ti 0 5. Otherwise let ti ti + 0+ or ti ti O with the same probability. ... All three strategies were tested on a set of ran domly generated problems as discussed next. ...
The process of project portfolio selection is crucial in many organizations, especially R&D organ... more The process of project portfolio selection is crucial in many organizations, especially R&D organizations. There is a need to make informed decisions on the investment in various projects or lack thereof. As the projects may continue over more than 1 year, and as there are connections between various projects, there is a need to not only decide which project to invest in but also when to invest. Since future benefits from projects are to be depreciated in comparison with near-future ones, and due to the interdependency among projects, the question of allocating the limited resources becomes quite complex. This research provides a novel heuristic method for allocating the limited resources over multi-annual planning horizons and examines its results in comparison with an exact branch and bound solution and various heuristic ones. This paper culminates with an efficient tool that can provide both practical and academic benefits.
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is ignored and assumed to have little to no effect. However, when the measuring scale step is not
negligible, it may affect statistical control tools such as X-chart. Designing statistical process
controls without considering the effects of rounding leads to high exposure to false negative results. This study illustrates the effects of rounding on the X-chart and shows that the result may
further deteriorate due to asymmetry (incompatibility of the process and the measuring device
parameters). A new simple method to design control limits is proposed, based on maintaining the
original characteristics of the chart as devised by Shewhart.
is ignored and assumed to have little to no effect. However, when the measuring scale step is not
negligible, it may affect statistical control tools such as X-chart. Designing statistical process
controls without considering the effects of rounding leads to high exposure to false negative results. This study illustrates the effects of rounding on the X-chart and shows that the result may
further deteriorate due to asymmetry (incompatibility of the process and the measuring device
parameters). A new simple method to design control limits is proposed, based on maintaining the
original characteristics of the chart as devised by Shewhart.