Reconstruction of set up and modification of template for the 4th laboratory exercise form Principles of Power Electronics

U ovom završnom radu dorađena je već izrađena maketa punovalnog poluupravljivog ispravljača u mosnom spoju i mjerenjem su uočeni nedostaci. Uočeni nedostaci su otklonjanji izbacivanjem transformatora za spoj ispravljača na pojnu mrežu. Odabrani su kutevi upravljanja za dva karakteristična režima rada. Dodatno je uvedeno mjerenje u-i karakteristike za oba kuta upravljanjaIn this final paper model of the full wave rectifier in a bridge connection was enhanced and measurements discovered some flaws. The observed flaws were removed by ejecting transformer from rectifier circuit. Conduction angels were selected for characteristic operating models. Additionally, it was introduced the measurement of u-i diagram for both conduction angles

SPINAL SURGERY IN INFLAMMATORY RHEUMATIC DISEASE

Najvažnije upalne reumatske bolesti kralježnice jesu reumatoidni artritis (RA) i bolesti skupine spondiloartritisa (SpA). U bolesnika s RA patološke promjene većinom zahvaćaju sinovijalne zglobove vratne kralježnice i izazivaju nestabilnu kralježnicu (subluksacija). Glavni tipovi subluksacija jesu: 1. prednja atlantoaksijalna subluksacija (AAS), 2. monosegmentne ili oligosegmentne subaksijalne subluksacije (SS) i 3. vertikalna subluksacija (VS). Vodeći je simptom vratobolja, a moguće su i kompresivne radikulopatije i mijelopatije s neurološkim defi citom. Pravodobno operacijsko liječenje subluksacija kod RA vratne kralježnice znatno smanjuje vratobolju i neurološke defi cite te snižava mortalitet. Kod AAS-a najčešće se rabi atlantoaksijalna transartikularna fi ksacija vijcima ili posterolateralna fiksacija atlasa s densom uz koštani presadak. VS se reponira i stabilizira okcipito-cervikalnom fuzijom, a SS se stabilizira posterolateralnom fuzijom s fiksacijom. Reumatoidne patološke promjene u slabinskoj kralježnici povisuju rizik od nastanka degenerativne spondilolisteze (dSPL) ili degenerativnog adultnog deformiteta (ASD), a liječe se operacijama prema principima za degenerativne bolesti kralježnice. Ankilozantni spondilitis (AS) aksijalni je oblik SpA, a najvažnija su mu klinička obilježja sakroileitis i spondilitis. Kod razvijene bolesti nastupaju osifikacija ligamenata aksijalnog skeleta, ankiloza vertebralnih zglobova, osteoporoza i kifotični deformitet. Kliničke manifestacije jesu: 1. ograničena pokretljivost kralježnice, 2. deformitet kralježnice s poremećajem ravnoteže, 3. sklonost nestabilnim prijelomima kralježnice. Cilj operacijskog liječenja ovih deformiteta jest omogućiti horizontalni pogled, korigirati ravnotežu, poboljšati hod i respiratornu funkciju te smanjiti bol. Danas se najčešće provodi klinasta zatvorena osteotomija tehnikom pedikularne suptrakcijske osteotomije (PSO), a svaku osteotomiju prati i dugačka unutarnja fi ksacija. Prijelome kralježnice u AS-u treba rano dijagnosticirati i zbrinjavati operacijom zbog izrazite nestabilnosti prijeloma i rizika od neurološkog pogoršanja i pseudoartroze. Princip operacije prijeloma jesu repozicija osi i dugačka fiksacija stražnjim pristupom. Upalne promjene u drugim oblicima SpA rijetko izazivaju promjene aksijalnog skeleta koje treba liječiti operacijom.The most significant inflammatory rheumatic diseases of the spine are rheumatoid arthritis (RA) and spondyloarthritis disease (SpA). In patients with RA, the pathological changes mostly affect the synovial joints of the cervical spine and cause an unstable spine (subluxation). The most common type of anatomical cervical spine deformity is atlantoaxial subluxation (AAS), followed by vertical subluxation (VS), and subaxial subluxation (SS). These anatomical deformities may cause neck pain and spinal cord or brainstem compression, with resultant neurological deficits such as cervical myelopathy, paresis, and even death. Early surgery may reduce the symptoms, neurological impairment,and mortality rate. AAS can be treated by atlantoaxial transarticular fixation or posterolateral fixation-fusion of the atlantoaxial segment. VS can be fixed by occipitocervical fusion and SS by posterior cervical fusion. Rheumatoid pathological changes increase the risk for the development of degenerative spondylolistesis (dSPL) or adult spinal deformities (ASD); operative treatment is performed according to protocols for degenerative spinal disorders. Ankylosing spondylitis (AS) is an axial spondyloarthritis which presents with ossifi cation of the axial skeleton ligaments, ankylosis of the vertebral joints, osteoporosis, and kyphotic spine deformity. Clinical manifestations are: 1. limited mobility of the spine; 2. spinal deformity with imbalance; and 3. unstable horizontal spine fractures. The major goals of AS surgery are stopping the natural course of progressive deformity, restoring the horizontal visual axis and global balance, improving disability, relieving the pain resulting from muscle fatigue, and improving respiratory function. The most commonly performed operative treatment is wedge closing osteotomy by pedicle subtraction osteotomy (PSO) with long internal fixation. Spine fracture in AS should be diagnosed in time and treated by surgery due to the marked instability of the fracture associated with an increased risk of neurological deterioration and pseudoarthrosis. Th e fracture operation is based on long segment fixation. Inflammatory changes in other forms of SpA rarely cause changes in the axial skeleton which require surgical treatment

Operation modes of the thyristor converter."SIMOREG"

U radu je analiziran rad tiristorskog usmjerivača Simoreg DC Master koji se sastoji od dva tiristorska mosta u antiparalelnom spoju. Kao regulirani pogonski stroj stavljen je istosmjerni motor s nezavisnom uzbudom. Analizirana su pogonska stanja motora te je prikazan 4-kvadratni rad pretvarača. Fokus je stavljen na analizu i prikaz načina prijelaza u radu pretvarača s jednog na drugi tiristorski most.This paper analyzes the operation of the thyristror converter Simoreg DC Master consisting of two thyristor bridges in an inverse-parallel. As a regulated drive it is installed a separately excited DC motor. It is analyzed and displayed four quadrant drive. The focus is placed on the analysis and presentation of the transmutation mode of operation from one to the other of the thyristor bridge

Treatment of Osteoporotic Fractures of the Spine

Osteoporotski prijelomi kralježnice dva do tri puta su učetaliji nego prijelomi kuka, posebice u žena. Vertebralni osteoporotski kompresijski prijelomi tipično uključuju srednju i donju torakalnu kralježnicu i torakolumbalni prijelaz. Klinička slika očituje se u akutnom stanju u obliku nagle boli u leđima nakon minimalne ozljede a često i kad ozljede nema. U dijagnostici je osnovno uzeti dobru anamnezu te provesti klinički pregled pacijenta. Temelj radiološke dijagnostike je standardni RTG. Ako postoji klinička indikacija (diferencijalna dijagnostika tumora ili spondilitisa, neurološka slabost) radi se i CT i/ili MR. Pristup liječenju osteoporotskih prijeloma kralježnice je individualan i temelji se na povijesti bolesti, lokalizaciji simptoma te korelaciji kliničkog pregleda i radiološkog nalaza. Česte su posljedice prijeloma dugotrajni bolovi, gubitak visine i deformacije kralježnice, koje znatno koreliraju sa smetnjama hoda i pokretljivosti, smanjenjem funkcije pluća, gubitkom teka i na kraju povećanom smrtnošću. Otvorena repozicija, dekompresija i fiksacija indicirana je u pacijenata s posttraumatskom stenozom i neurološkom slabošću. Moderne kirurške tehnike liječenja su vertebroplastika i kifoplastika koje znatno smanjuju bol i poboljšavaju pokretljivost pacijenata, a time i kvalitetu života.Osteoporosis is a skeletal disease characterized by reduced bone strength due to the loss of bone mass, structural disproportion and reduced calcium level as well as changes in the bone structure caused by trabecular deficit. The loss of bone mass in the vertebrae leads to an increased risk of fractures. Osteoporotic vertebral fractures are two to three times more frequent than hip fractures, especially in women. Osteoporotic compressive fractures of the spine mostly occur in the middle and lower thoracic spine and in the thoracolumbar spine. Common consequences of fractures include long-term pains, decrease in the height and spinal deformity, which significantly correlate with disorders in the gait and mobility, reduced pulmonary function, loss of appetite and in the end increased mortality. Clinical picture in acute conditions manifests itself as a sudden pain in the back following minimal trauma but also often without any trauma at all. Diagnostics is based on a detailed medical history and a thorough clinical examination. Radiological diagnosis relies on standard x-rays. In case of clinical indication (differential diagnosis of tumor or spondylitis, neurological weakness) CT and/or MR imaging is performed. The approach to the treatment of osteoporotic fractures of the spine is individual and is based upon the medical history, localization of symptoms and correlation of the clinical examination with the radiological finding. Open reduction, decompression and fixation are indicated in patients with posttraumatic stenosis and neurological weakness. Current operative methods include vertebroplasty and kyphoplasty, which significantly reduce pain and improve mobility of the patient and consequently, the quality of life