63 research outputs found
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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
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