New variants of variable neighbourhood search for 0-1 mixed integer programming and clustering

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.Many real-world optimisation problems are discrete in nature. Although recent rapid developments in computer technologies are steadily increasing the speed of computations, the size of an instance of a hard discrete optimisation problem solvable in prescribed time does not increase linearly with the computer speed. This calls for the development of new solution methodologies for solving larger instances in shorter time. Furthermore, large instances of discrete optimisation problems are normally impossible to solve to optimality within a reasonable computational time/space and can only be tackled with a heuristic approach. In this thesis the development of so called matheuristics, the heuristics which are based on the mathematical formulation of the problem, is studied and employed within the variable neighbourhood search framework. Some new variants of the variable neighbourhood searchmetaheuristic itself are suggested, which naturally emerge from exploiting the information from the mathematical programming formulation of the problem. However, those variants may also be applied to problems described by the combinatorial formulation. A unifying perspective on modern advances in local search-based metaheuristics, a so called hyper-reactive approach, is also proposed. Two NP-hard discrete optimisation problems are considered: 0-1 mixed integer programming and clustering with application to colour image quantisation. Several new heuristics for 0-1 mixed integer programming problem are developed, based on the principle of variable neighbourhood search. One set of proposed heuristics consists of improvement heuristics, which attempt to find high-quality near-optimal solutions starting from a given feasible solution. Another set consists of constructive heuristics, which attempt to find initial feasible solutions for 0-1 mixed integer programs. Finally, some variable neighbourhood search based clustering techniques are applied for solving the colour image quantisation problem. All new methods presented are compared to other algorithms recommended in literature and a comprehensive performance analysis is provided. Computational results show that the methods proposed either outperform the existing state-of-the-art methods for the problems observed, or provide comparable results. The theory and algorithms presented in this thesis indicate that hybridisation of the CPLEX MIP solver and the VNS metaheuristic can be very effective for solving large instances of the 0-1 mixed integer programming problem. More generally, the results presented in this thesis suggest that hybridisation of exact (commercial) integer programming solvers and some metaheuristic methods is of high interest and such combinations deserve further practical and theoretical investigation. Results also show that VNS can be successfully applied to solving a colour image quantisation problem.Support from the Mathematical Institute, Serbian Academy of Sciences and Arts, are acknowledged for this research

Variational image regularization with Euler's elastica using a discrete gradient scheme

This paper concerns an optimization algorithm for unconstrained non-convex problems where the objective function has sparse connections between the unknowns. The algorithm is based on applying a dissipation preserving numerical integrator, the Itoh--Abe discrete gradient scheme, to the gradient flow of an objective function, guaranteeing energy decrease regardless of step size. We introduce the algorithm, prove a convergence rate estimate for non-convex problems with Lipschitz continuous gradients, and show an improved convergence rate if the objective function has sparse connections between unknowns. The algorithm is presented in serial and parallel versions. Numerical tests show its use in Euler's elastica regularized imaging problems and its convergence rate and compare the execution time of the method to that of the iPiano algorithm and the gradient descent and Heavy-ball algorithms

From waste streams to biotherapeutics: making a connection using bacteria

Microorganisms, our planet’s original inhabitants discovered with the invention of the first microscope in the 17th century, have consistently facilitated our daily life. However, our modern life generates enormous amounts of wastes, such as plastic, food, and chemicals from the pharmaceutical industry. Bacterial natural products hold an important position in this industry, as drug leads in synthetic chemistry and biology, essential for the discovery of effective agents against a variety of human diseases. If the existing waste is used as a nutrient source for microbial production of valuable biomolecules, that concept is called “waste to value” or “upcycling”. This concept was explored using bacterial biopigment prodigiosin (PG, Fig. 1) as part of the BioECOLogics project. This proof of concept demonstrates how the bacteria Serratia marcescens ATCC 27117 can use a waste stream from the food industry as a carbon source to grow and produce its bioactive secondary metabolite PG. The unique structure of this molecule was changed through green chemical [1] and biopolymer formulation [2] approaches, as well as metal complexation. Finally, these sustainable biotherapeutics were validated in vitro (antimicrobial, anticancer) and in vivo (nematode Caenorhabditis elegans and zebrafish Danio rerio).Book of Abstracts: 9th Conference of Young Chemists of Serbia Novi Sad, 4th November 202

The performance of pip-cascade controler in hvac system

Primitive controllers used in the early version for HVAC systems, like the on-off (Bang-Bang) controller, are inefficient, inaccurate, unstable, and suffer from high-level mechanical wear. On the other hand, other controllers like PI and cascade controllers, overcome these disadvantages but when an offset response (inaccurate response) occurs, power consumption will increase. In order to acquire better performance in the central air-conditioning system, PIP-cascade control is investigated in this paper and compared to the traditional PI and PID, in simulation of experimental data. The output of the system is predicted through disturbances. Based on the mathematical model of air-conditioning space, the simulations in this paper have found that the PIP-cascade controller has the capability of self-adapting to system changes and results in faster response and better performance

The performance of pip-cascade controler in hvac system

Primitive controllers used in the early version for HVAC systems, like the on-off (Bang-Bang) controller, are inefficient, inaccurate, unstable, and suffer from high-level mechanical wear. On the other hand, other controllers like PI and cascade controllers, overcome these disadvantages but when an offset response (inaccurate response) occurs, power consumption will increase. In order to acquire better performance in the central air-conditioning system, PIP-cascade control is investigated in this paper and compared to the traditional PI and PID, in simulation of experimental data. The output of the system is predicted through disturbances. Based on the mathematical model of air-conditioning space, the simulations in this paper have found that the PIP-cascade controller has the capability of self-adapting to system changes and results in faster response and better performance

Evaluation of Fixed Prosthodontic Appliances after Five Years of Use Using Orthopantomographic Screening in Relation to Material

Svrha ovog istraživanja bila je pregledati one pacijente, i njihove ortopantomograme, koji su u usnoj šupljini imali fiksnoprotetski rad stariji od 5 godina kako bi se ustanovila čestoća karijesa i čestoća parodontnih džepova dubljih od 3 mm. Osim toga, željelo se je ustanoviti postojanje razlika u čestoći patoloških nalaza ovisno o vrsti različitih fiksnoprotetskih konstrukcija, te postoji li razlika između zuba nosača različitih krunica i nenosača krunica (nebrušenih zuba). Sudjelovalo je 260 pacijenata (55% žena i 45% muškaraca) u dobi od 25 do 70 godina koji nikada nisu imali problema s fiksnoprotetskim radom te su njime bili potpuno zadovoljni. Na 260 ortopantomograma ukupno je analizirano 2265 zuba; 864 zuba nosača krunica uključenih u mostove, 407 zuba nosača samostalnih krunica, a preostali zubi bili su nenosači krunica. Rezultati su pokazali razmjerno veliku čestoću patoloških nalaza (karijes, džepovi > 3 mm) u nosilaca fiksnoprotetskih radova koji su bili stariji od 5 godina. Parodontni problemi bili su češći od karijesa. Najveća čestoća patoloških nalaza bila je kod krunica s akrilatnom fasetom, a najmanja kod keramičkih radova (p0,05). U incidenciji karijesa nije bilo statistički znatne razlike (p>0,05), a u incidenciji džepova nenosači i nosači keramičkih radova imali su znatno manje džepova od nosača fasetiranih ili potpunih metalnih krunica (p 3 mm) in patients with FPDs older than 5 years. Periodontal pockets were more frequent than cervical caries. The highest frequency of pathologic findings was registered for abutments with metal acrylic crowns, and the lowest frequency of pathologic findings was registered for abutments with metal-ceramic crowns (p0.05). There were no significant differences in caries incidence between the examined teeth (p>0.05). Non-abutment teeth and abutments of metal-ceramic crowns had significantly lower frequency of pockets deeper than 3 mm than abutments of metal acrylic and full metallic crowns (p<0.05)

Auditive-verbal and behavioral functioning of the children with intelectual disabilities

Ovako definisana empirijska studija pokušava da odgovori na problem specifičnih veza izme�����u individualnih razvojnih karakteristika ispitane dece, posmatranih kroz standardnu situaciju edukacije u momentu kada je istraživanje izvedeno. Rad je konceptualno baziran na ispitivanju perceptivnih i bihejvioralnih razvojnih dimenzija i manifestacija dece sa intelektualnom ometenošću. Interesovanje autora usmereno je na utvr�����ivanje povezanosti auditivno-verbalnog i socijalnog funkcionisanja ispitanog uzorka. To determiniše praktične implikacije rada - inkluzivne edukacije, s jedne strane i multimodalnog tretmana bihejvioralnih smetnji, s druge strane. Slučajan uzorak formiran je od ispitanika sa lakom intelektualnom ometenošću, oba pola koji poha�����aju osnovne škole u Beogradu. Auditivno-verbalne sposobnosti ispitane su Token testom, a ponašanje Konersovom skalom procene kojom se dobija uvid u ponašanje i pažnju u uslovima edukacije. Utvr�����eno je postojanje statistički signifikatne korelacije me�����u ispitanim varijablama i ukazano na konceptualne i praktične mogućnosti izvo�����enja multimodalno orijentisanog tretmana.The study deals up with auditive, verbal and behavioral functioning of the children with mild intellectual disabilities. The sample was formed of the 124 children with mild intellectual disabilities, both gender, chronologicaly distributed form 8 to 13 years. We asses auditive-verbal functions by the Test of Concept Utilization (R. L. Crager & S. U. Lane, 1981), attention by Trail Making Test - TMT (Reitan, 1971) and behavior by Conners Rating Scale (K.Conners, 1969). Results points up the high statistical relationship between the tested variables such as behavior, voluntary attention and auditive-verbal functions. On the base of the results of the study we conclude about the significance of implementation of the multimodal oriented approach, in which the central professional role is played by special educator in its final implementation

Auditive-verbal and behavioral functioning of the children with intelectual disabilities

Ovako definisana empirijska studija pokušava da odgovori na problem specifičnih veza izme�����u individualnih razvojnih karakteristika ispitane dece, posmatranih kroz standardnu situaciju edukacije u momentu kada je istraživanje izvedeno. Rad je konceptualno baziran na ispitivanju perceptivnih i bihejvioralnih razvojnih dimenzija i manifestacija dece sa intelektualnom ometenošću. Interesovanje autora usmereno je na utvr�����ivanje povezanosti auditivno-verbalnog i socijalnog funkcionisanja ispitanog uzorka. To determiniše praktične implikacije rada - inkluzivne edukacije, s jedne strane i multimodalnog tretmana bihejvioralnih smetnji, s druge strane. Slučajan uzorak formiran je od ispitanika sa lakom intelektualnom ometenošću, oba pola koji poha�����aju osnovne škole u Beogradu. Auditivno-verbalne sposobnosti ispitane su Token testom, a ponašanje Konersovom skalom procene kojom se dobija uvid u ponašanje i pažnju u uslovima edukacije. Utvr�����eno je postojanje statistički signifikatne korelacije me�����u ispitanim varijablama i ukazano na konceptualne i praktične mogućnosti izvo�����enja multimodalno orijentisanog tretmana.The study deals up with auditive, verbal and behavioral functioning of the children with mild intellectual disabilities. The sample was formed of the 124 children with mild intellectual disabilities, both gender, chronologicaly distributed form 8 to 13 years. We asses auditive-verbal functions by the Test of Concept Utilization (R. L. Crager & S. U. Lane, 1981), attention by Trail Making Test - TMT (Reitan, 1971) and behavior by Conners Rating Scale (K.Conners, 1969). Results points up the high statistical relationship between the tested variables such as behavior, voluntary attention and auditive-verbal functions. On the base of the results of the study we conclude about the significance of implementation of the multimodal oriented approach, in which the central professional role is played by special educator in its final implementation

Intellectual disabilities and organogenetics disturbances – strategies of treatment

Intelektualna ometenost prema novijim shvatanjima podrazumeva posebne potrebe u brojnim razvojnim domenima. Ove specifičnosti razvoja u krajnjem vidu rezultiraju brojnim kognitivnim i konativnim disfunkcijama, a tako�����e i somatskim anomalijama. Dentalne anlomalije kao posledice poremećaja organogeneze značajno participiraju u poremećajima komunikacije i somatskog stanja u smislu gastrointestinalnih tegoba. Terapijski pristup baziran je na stomatološkim interevencijama kao i lečenju gastrointestinalnih posledica uz obavezan tretman defektologa, psihijatra i specijaliste interne medicine.Ovaj rad pokušava da ukaže na to koliko udeo pripada svim navedenim činiocima u formiranju složene kliničke slike intelektualne ometenosti? Istraživanjem je obuhvaćen uzorak od 54 osobe sa intelektualnom ometenošću u Beogradu.. Korišćeni su psihološki podaci o kategorizaciji i stomatološki kartoni istih kao i ostala prateća dostupna medicinska dokumentacija. Korišćene su odgovarajuće statističke metode u prikazivanju i obradi dobijenih podataka deskriptivne studije. U radu su prezentirani dostupni podaci multidisciplinarne obrade ispitanika u odnosu na dostupne ispitivane varijable navedene u uvodnom delu rada i dovedene u vezu sa osnovnom kliničkom slikom uzorka. Finalna razmatranja ukazuju na potrebu sistematizovanog pristupa brojnih naučnih disciplina i profesija u definisanju adekvatnog tretmana osoba sa intelektualnom ometenošću u skladu sa njihovim razvojnim potrebama gde centralno mesto pripada defektologu kao profesionalnoj figuri oko koje se fokusiraju rehabilitacione strategije u ovoj oblasti.On the base of many multidisciplinary approach intellectual disabilities are the state of special developmental needs. These specifities result in many cognitive, conative and somatic disorders. Dental disorders as organogenesis disorder significantly participated in disorders of communication, somatic disorders and disorders of gastrointestive tract. That is why we try to estimate the frequency of these disorders in forming the whole simptomathology of intellectual disabilities. Research sample was formed of 54 children with intellectual disabilities from Belgrade. We present the results of multidisciplinary assessment of participants and connected them with the basic variables of research. Final conclusion point out the significance of the adequate treatment of the children with intellectual disabilities with central professional role of the special educator

Intellectual disabilities and organogenetics disturbances – strategies of treatment

Intelektualna ometenost prema novijim shvatanjima podrazumeva posebne potrebe u brojnim razvojnim domenima. Ove specifičnosti razvoja u krajnjem vidu rezultiraju brojnim kognitivnim i konativnim disfunkcijama, a tako�����e i somatskim anomalijama. Dentalne anlomalije kao posledice poremećaja organogeneze značajno participiraju u poremećajima komunikacije i somatskog stanja u smislu gastrointestinalnih tegoba. Terapijski pristup baziran je na stomatološkim interevencijama kao i lečenju gastrointestinalnih posledica uz obavezan tretman defektologa, psihijatra i specijaliste interne medicine.Ovaj rad pokušava da ukaže na to koliko udeo pripada svim navedenim činiocima u formiranju složene kliničke slike intelektualne ometenosti? Istraživanjem je obuhvaćen uzorak od 54 osobe sa intelektualnom ometenošću u Beogradu.. Korišćeni su psihološki podaci o kategorizaciji i stomatološki kartoni istih kao i ostala prateća dostupna medicinska dokumentacija. Korišćene su odgovarajuće statističke metode u prikazivanju i obradi dobijenih podataka deskriptivne studije. U radu su prezentirani dostupni podaci multidisciplinarne obrade ispitanika u odnosu na dostupne ispitivane varijable navedene u uvodnom delu rada i dovedene u vezu sa osnovnom kliničkom slikom uzorka. Finalna razmatranja ukazuju na potrebu sistematizovanog pristupa brojnih naučnih disciplina i profesija u definisanju adekvatnog tretmana osoba sa intelektualnom ometenošću u skladu sa njihovim razvojnim potrebama gde centralno mesto pripada defektologu kao profesionalnoj figuri oko koje se fokusiraju rehabilitacione strategije u ovoj oblasti.On the base of many multidisciplinary approach intellectual disabilities are the state of special developmental needs. These specifities result in many cognitive, conative and somatic disorders. Dental disorders as organogenesis disorder significantly participated in disorders of communication, somatic disorders and disorders of gastrointestive tract. That is why we try to estimate the frequency of these disorders in forming the whole simptomathology of intellectual disabilities. Research sample was formed of 54 children with intellectual disabilities from Belgrade. We present the results of multidisciplinary assessment of participants and connected them with the basic variables of research. Final conclusion point out the significance of the adequate treatment of the children with intellectual disabilities with central professional role of the special educator