Train Scheduling on a Unidirectional Path

We formulate what might be the simplest train scheduling problem considered in the literature and show it to be NP-hard. We also give a log-factor randomised algorithm for it. In our problem we have a unidirectional train track with equidistant stations, each station initially having at most one train. In addition, there can be at most one train poised to enter each station. The trains must move to their destinations subject to the constraint that at every time instant there can be at most one train at each station and on the track between stations. The goal is to minimise the maximum delay of any train. Our problem can also be interpreted as a packet routing problem, and our work strengthens the hardness results from that literature

Produktionsplanering med Last Planner systemet på byggprojekt i Sverige : En explorativ fallstudie av utmaningar och förbättringsåtgärder

One of the main assumptions in conventional production process is that each component or part of the production process can be controlled separately as if they are not dependent on anything. This assumption gives rise to problems such as need of effective collaboration with different actors and constraints in budgets. Conventional planning process also causes delay as well as cost overruns which ultimately leads to reduction in productivity.The Last Planner system, LPS, is a tool used in the construction sector with the goal of streamlining production. The tool has several advantages, for example, to make collaboration between different actors more efficient, achieve a better workflow and increase production efficiency. The purpose of this masters’ thesis is to explore how two construction projects in Stockholm work with LPS. Apart from the fact that LPS provides many advantages in the production planning of the projects, this study aims to explore the challenges that they face while working with LPS. The goal of this study is to be able to suggest improvement measures for the challenges that the projects are facing.Semi-structured interviews were conducted on both projects to understand how they work with LPS and what challenges they face. The results section contains the information from the interviews. That is then discussed against the theory on which the Last Planner system is built.The conclusion of this study is that the production planning in the projects differs from how the tool should be used according to the framework of LPS. Learning, which emphasizes what has been done during the project, is a phase in LPS's framework. According to one of the founders of the LPS system, ‘learning’ is the most important phase. However, due to the lack of time, the studied projects were not able to involve the learning phase into their production planning. The projects faced several challenges, including repeated changes from the design teams, which entailed new actions during the project. Also, the involvement of the construction workers in the planning phases came out as a big challenge for the managers. Furthermore, communication problems and lack of cooperation with subcontractors is also present. Some of the improvement measures suggested to meet the challenges are that managers should increase commitment to involve especially construction workers in the planning phases, create nucleus teams, create a standard protocol for how production planning should be implemented, and improve visual planning to enhance communication.I de traditionella produktionsprocesserna har det antagits att olika komponenter kan styras separat d.v.s. att de är oberoende. Detta antagandet har gett upphov till problem som till exempel försämrat samarbete mellan olika aktörer. Den traditionella produktionsprocessen har också lett till förseningar och kostnadsöverskridanden i projekt.Last Planner-systemet, LPS, är ett verktyg som används inom byggsektorn med målet att effektivisera produktionen. Förutom att effektivisera produktionen är syftet att involvera byggarbetare i planeringsfaserna. Verktyget har flera fördelar, till exempel att effektivisera samarbeten mellan olika aktörer, uppnå ett konstant arbetsflöde och ökad effektivitet i produktionen. Syftet med denna uppsats är att utforska hur två byggprojekt i Stockholm arbetar med LPS. Bortsett från att LPS tillför många fördelar i projektens produktionsplanering har denna uppsats som mål att utforska vilka utmaningar projekten står inför kring arbetet med LPS. Målet är att kunna föreslå eventuella förbättringar för att möta utmaningarna som projekten står inför.Semistrukturerade intervjuer genomfördes på båda projekten för att förstå hur de arbetar med LPS och vilka utmaningar de står inför. Resultatavsnittet redovisar informationen från intervjuerna, som sedan diskuteras i relation till teorin som LPS bygger på.Slutsatsen av denna uppsats är att det skiljer sig mellan hur verktyget används i praktiken jämfört med vad ramverket för LPS står för. Att ta lärdom av vad som gjorts under projektet är en fas i LPS ramverk. Enligt en av grundarna av LPS-systemet är ’lärande’ den viktigaste fasen. Men på grund av tidsbrist har inte projekten som denna studie undersökte kunnat genomföra den fasen. Projekten stod inför flera utmaningar, bland annat upprepade ändringar från designteamen, som ledde till nya åtgärder under projektet, att involvera byggarbetare i planeringsfaserna, kommunikationsproblem mellan aktörer och bristande samarbete med underentreprenörer. Några förbättringsåtgärder är att chefer borde engagera sig mer för att involvera byggarbetare i planeringsfaserna, skapa ett standardprotokoll för hur produktionsplanering bör genomföras och förbättra den visuella planeringen för att uppnå bättre kommunikation

Produktionsplanering med Last Planner systemet på byggprojekt i Sverige : En explorativ fallstudie av utmaningar och förbättringsåtgärder

One of the main assumptions in conventional production process is that each component or part of the production process can be controlled separately as if they are not dependent on anything. This assumption gives rise to problems such as need of effective collaboration with different actors and constraints in budgets. Conventional planning process also causes delay as well as cost overruns which ultimately leads to reduction in productivity.The Last Planner system, LPS, is a tool used in the construction sector with the goal of streamlining production. The tool has several advantages, for example, to make collaboration between different actors more efficient, achieve a better workflow and increase production efficiency. The purpose of this masters’ thesis is to explore how two construction projects in Stockholm work with LPS. Apart from the fact that LPS provides many advantages in the production planning of the projects, this study aims to explore the challenges that they face while working with LPS. The goal of this study is to be able to suggest improvement measures for the challenges that the projects are facing.Semi-structured interviews were conducted on both projects to understand how they work with LPS and what challenges they face. The results section contains the information from the interviews. That is then discussed against the theory on which the Last Planner system is built.The conclusion of this study is that the production planning in the projects differs from how the tool should be used according to the framework of LPS. Learning, which emphasizes what has been done during the project, is a phase in LPS's framework. According to one of the founders of the LPS system, ‘learning’ is the most important phase. However, due to the lack of time, the studied projects were not able to involve the learning phase into their production planning. The projects faced several challenges, including repeated changes from the design teams, which entailed new actions during the project. Also, the involvement of the construction workers in the planning phases came out as a big challenge for the managers. Furthermore, communication problems and lack of cooperation with subcontractors is also present. Some of the improvement measures suggested to meet the challenges are that managers should increase commitment to involve especially construction workers in the planning phases, create nucleus teams, create a standard protocol for how production planning should be implemented, and improve visual planning to enhance communication.I de traditionella produktionsprocesserna har det antagits att olika komponenter kan styras separat d.v.s. att de är oberoende. Detta antagandet har gett upphov till problem som till exempel försämrat samarbete mellan olika aktörer. Den traditionella produktionsprocessen har också lett till förseningar och kostnadsöverskridanden i projekt.Last Planner-systemet, LPS, är ett verktyg som används inom byggsektorn med målet att effektivisera produktionen. Förutom att effektivisera produktionen är syftet att involvera byggarbetare i planeringsfaserna. Verktyget har flera fördelar, till exempel att effektivisera samarbeten mellan olika aktörer, uppnå ett konstant arbetsflöde och ökad effektivitet i produktionen. Syftet med denna uppsats är att utforska hur två byggprojekt i Stockholm arbetar med LPS. Bortsett från att LPS tillför många fördelar i projektens produktionsplanering har denna uppsats som mål att utforska vilka utmaningar projekten står inför kring arbetet med LPS. Målet är att kunna föreslå eventuella förbättringar för att möta utmaningarna som projekten står inför.Semistrukturerade intervjuer genomfördes på båda projekten för att förstå hur de arbetar med LPS och vilka utmaningar de står inför. Resultatavsnittet redovisar informationen från intervjuerna, som sedan diskuteras i relation till teorin som LPS bygger på.Slutsatsen av denna uppsats är att det skiljer sig mellan hur verktyget används i praktiken jämfört med vad ramverket för LPS står för. Att ta lärdom av vad som gjorts under projektet är en fas i LPS ramverk. Enligt en av grundarna av LPS-systemet är ’lärande’ den viktigaste fasen. Men på grund av tidsbrist har inte projekten som denna studie undersökte kunnat genomföra den fasen. Projekten stod inför flera utmaningar, bland annat upprepade ändringar från designteamen, som ledde till nya åtgärder under projektet, att involvera byggarbetare i planeringsfaserna, kommunikationsproblem mellan aktörer och bristande samarbete med underentreprenörer. Några förbättringsåtgärder är att chefer borde engagera sig mer för att involvera byggarbetare i planeringsfaserna, skapa ett standardprotokoll för hur produktionsplanering bör genomföras och förbättra den visuella planeringen för att uppnå bättre kommunikation

Produktionsplanering med Last Planner systemet på byggprojekt i Sverige : En explorativ fallstudie av utmaningar och förbättringsåtgärder

One of the main assumptions in conventional production process is that each component or part of the production process can be controlled separately as if they are not dependent on anything. This assumption gives rise to problems such as need of effective collaboration with different actors and constraints in budgets. Conventional planning process also causes delay as well as cost overruns which ultimately leads to reduction in productivity.The Last Planner system, LPS, is a tool used in the construction sector with the goal of streamlining production. The tool has several advantages, for example, to make collaboration between different actors more efficient, achieve a better workflow and increase production efficiency. The purpose of this masters’ thesis is to explore how two construction projects in Stockholm work with LPS. Apart from the fact that LPS provides many advantages in the production planning of the projects, this study aims to explore the challenges that they face while working with LPS. The goal of this study is to be able to suggest improvement measures for the challenges that the projects are facing.Semi-structured interviews were conducted on both projects to understand how they work with LPS and what challenges they face. The results section contains the information from the interviews. That is then discussed against the theory on which the Last Planner system is built.The conclusion of this study is that the production planning in the projects differs from how the tool should be used according to the framework of LPS. Learning, which emphasizes what has been done during the project, is a phase in LPS's framework. According to one of the founders of the LPS system, ‘learning’ is the most important phase. However, due to the lack of time, the studied projects were not able to involve the learning phase into their production planning. The projects faced several challenges, including repeated changes from the design teams, which entailed new actions during the project. Also, the involvement of the construction workers in the planning phases came out as a big challenge for the managers. Furthermore, communication problems and lack of cooperation with subcontractors is also present. Some of the improvement measures suggested to meet the challenges are that managers should increase commitment to involve especially construction workers in the planning phases, create nucleus teams, create a standard protocol for how production planning should be implemented, and improve visual planning to enhance communication.I de traditionella produktionsprocesserna har det antagits att olika komponenter kan styras separat d.v.s. att de är oberoende. Detta antagandet har gett upphov till problem som till exempel försämrat samarbete mellan olika aktörer. Den traditionella produktionsprocessen har också lett till förseningar och kostnadsöverskridanden i projekt.Last Planner-systemet, LPS, är ett verktyg som används inom byggsektorn med målet att effektivisera produktionen. Förutom att effektivisera produktionen är syftet att involvera byggarbetare i planeringsfaserna. Verktyget har flera fördelar, till exempel att effektivisera samarbeten mellan olika aktörer, uppnå ett konstant arbetsflöde och ökad effektivitet i produktionen. Syftet med denna uppsats är att utforska hur två byggprojekt i Stockholm arbetar med LPS. Bortsett från att LPS tillför många fördelar i projektens produktionsplanering har denna uppsats som mål att utforska vilka utmaningar projekten står inför kring arbetet med LPS. Målet är att kunna föreslå eventuella förbättringar för att möta utmaningarna som projekten står inför.Semistrukturerade intervjuer genomfördes på båda projekten för att förstå hur de arbetar med LPS och vilka utmaningar de står inför. Resultatavsnittet redovisar informationen från intervjuerna, som sedan diskuteras i relation till teorin som LPS bygger på.Slutsatsen av denna uppsats är att det skiljer sig mellan hur verktyget används i praktiken jämfört med vad ramverket för LPS står för. Att ta lärdom av vad som gjorts under projektet är en fas i LPS ramverk. Enligt en av grundarna av LPS-systemet är ’lärande’ den viktigaste fasen. Men på grund av tidsbrist har inte projekten som denna studie undersökte kunnat genomföra den fasen. Projekten stod inför flera utmaningar, bland annat upprepade ändringar från designteamen, som ledde till nya åtgärder under projektet, att involvera byggarbetare i planeringsfaserna, kommunikationsproblem mellan aktörer och bristande samarbete med underentreprenörer. Några förbättringsåtgärder är att chefer borde engagera sig mer för att involvera byggarbetare i planeringsfaserna, skapa ett standardprotokoll för hur produktionsplanering bör genomföras och förbättra den visuella planeringen för att uppnå bättre kommunikation

Decoding the neural signatures of valence and arousal from portable EEG headset

ne pas intégrer à la collection IEMN (travaux de Master)International audienceEmotion classification using electroencephalography (EEG) data and machine learning techniques have been on the rise in the recent past. However, past studies use data from medical-grade EEG setups with long set-up times and environment constraints. This paper focuses on classifying emotions on the valence-arousal plane using various feature extraction, feature selection, and machine learning techniques. We evaluate different feature extraction and selection techniques and propose the optimal set of features and electrodes for emotion recognition. The images from the OASIS image dataset were used to elicit valence and arousal emotions, and the EEG data was recorded using the Emotiv Epoc X mobile EEG headset. The analysis is carried out on publicly available datasets: DEAP and DREAMER for benchmarking. We propose a novel feature ranking technique and incremental learning approach to analyze performance dependence on the number of participants. Leave-one-subject-out cross-validation was carried out to identify subject bias in emotion elicitation patterns. The importance of different electrode locations was calculated, which could be used for designing a headset for emotion recognition. The collected dataset and pipeline are also published. Our study achieved a root mean square score (RMSE) of 0.905 on DREAMER, 1.902 on DEAP, and 2.728 on our dataset for valence label and a score of 0.749 on DREAMER, 1.769 on DEAP, and 2.3 on our proposed dataset for arousal label

Data_Sheet_1_Decoding the neural signatures of valence and arousal from portable EEG headset.PDF

Emotion classification using electroencephalography (EEG) data and machine learning techniques have been on the rise in the recent past. However, past studies use data from medical-grade EEG setups with long set-up times and environment constraints. This paper focuses on classifying emotions on the valence-arousal plane using various feature extraction, feature selection, and machine learning techniques. We evaluate different feature extraction and selection techniques and propose the optimal set of features and electrodes for emotion recognition. The images from the OASIS image dataset were used to elicit valence and arousal emotions, and the EEG data was recorded using the Emotiv Epoc X mobile EEG headset. The analysis is carried out on publicly available datasets: DEAP and DREAMER for benchmarking. We propose a novel feature ranking technique and incremental learning approach to analyze performance dependence on the number of participants. Leave-one-subject-out cross-validation was carried out to identify subject bias in emotion elicitation patterns. The importance of different electrode locations was calculated, which could be used for designing a headset for emotion recognition. The collected dataset and pipeline are also published. Our study achieved a root mean square score (RMSE) of 0.905 on DREAMER, 1.902 on DEAP, and 2.728 on our dataset for valence label and a score of 0.749 on DREAMER, 1.769 on DEAP, and 2.3 on our proposed dataset for arousal label.</p

A Literature-Derived Knowledge Graph Augments the Interpretation of Single Cell RNA-seq Datasets

Technology to generate single cell RNA-sequencing (scRNA-seq) datasets and tools to annotate them have advanced rapidly in the past several years. Such tools generally rely on existing transcriptomic datasets or curated databases of cell type defining genes, while the application of scalable natural language processing (NLP) methods to enhance analysis workflows has not been adequately explored. Here we deployed an NLP framework to objectively quantify associations between a comprehensive set of over 20,000 human protein-coding genes and over 500 cell type terms across over 26 million biomedical documents. The resultant gene-cell type associations (GCAs) are significantly stronger between a curated set of matched cell type-marker pairs than the complementary set of mismatched pairs (Mann Whitney p = 6.15 × 10−76, r = 0.24; cohen’s D = 2.6). Building on this, we developed an augmented annotation algorithm (single cell Annotation via Literature Encoding, or scALE) that leverages GCAs to categorize cell clusters identified in scRNA-seq datasets, and we tested its ability to predict the cellular identity of 133 clusters from nine datasets of human breast, colon, heart, joint, ovary, prostate, skin, and small intestine tissues. With the optimized settings, the true cellular identity matched the top prediction in 59% of tested clusters and was present among the top five predictions for 91% of clusters. scALE slightly outperformed an existing method for reference data driven automated cluster annotation, and we demonstrate that integration of scALE can meaningfully improve the annotations derived from such methods. Further, contextualization of differential expression analyses with these GCAs highlights poorly characterized markers of well-studied cell types, such as CLIC6 and DNASE1L3 in retinal pigment epithelial cells and endothelial cells, respectively. Taken together, this study illustrates for the first time how the systematic application of a literature-derived knowledge graph can expedite and enhance the annotation and interpretation of scRNA-seq data