Smoke Cloak – New Conception in Object and Facilities Protection

Svjedoci smo gotovo svakodnevnih provala u našoj neposrednoj okolini i svugdje u svijetu. Provalnici su sve smjeliji i provaljuju u svako doba dana i noći u objekte poput banaka, poštanskih ureda, kladionica, mjenjačnica i slične prostore u kojima je postavljena visoka razina zaštite (zaštitari i sredstva tehničke zaštite). Unatoč tome provale su učestale. Zbog toga se pristupilo osmišljavanju novih koncepcija i strategija osiguravanja objekata i prostora. Jedan od uspješnih koncepata je i zaštita dimom ili dimnom zavjesom. Idejni princip rada ovog sustava je u prevenciji krađe je: „Ne može se ukrasti ono što se ne vidi“. Sustav dimne zavjese radi tako da u vrlo kratkom vremenu ispunjava prostoriju bezopasnim dimom kako bi provalniku smanjio vidljivost i tako ga psihološki dezorijentirao, osujetio i odvratio od daljnjih aktivnosti. Ovaj novi sustavni pristup za dezorijentaciju kao protuprepadni sustav počeo se sve više primjenjivati (NATO ga koristi kao dio sustava za zaštitu tankera od gusara) i do sada se pokazao izuzetno učinkovit.lmost daily we are witnesses to burglaries in our immediate environment. The burglars are more audacious and they break in at any time of day and night in buildings such as banks, post offices, betting office, exchange office and places in which high level of protection (security guards and means of technical protection) are set up. Despite that, the burglaries are very ommon. Therefore, a new conception has been made to secure objects and indoors and outdoors of buildings. One of them is the smoke cloak or smoke screen. The principle of this stealing prevention system is “You can not steal what you can not see”. Smoke cloak system in a very short time fills the oom with harmless smoke in order to totally reduce visibility. The burglar is psychologically disoriented, frustrated and discouraged for further activities. This new systematic approach to disorientationas anti-foray system, began to be increasingly applied (NATO uses it as part of system to protect tanker ships from pirates), and so far it has proved very effective

Modelling of electric characteristics of the photovoltaic amorphous-nanocrystalline silicon cell

U radu su opisana poluvodička svojstva silicija, hetero-spojevi silicija, istražen je foto-naponski efekt u intrinzičnom sloju, odnosno, generacija i rekombinacija slobodnih nosioca naboja. Opisane su fizikalne osnove jednoslojnih solarnih ćelija izrađenih od silicija, a predočen je amorfno-nanokristalinični silicij kao vrlo značajni kompozitni poluvodički materijal za izradu foto-naponskih ćelija visoke efikasnosti, takozvane solarne ćelije treće generacije. Navedene su strukturne, optičke i električne karakteristike tankih nc-Si:H filmova ustanovljenih različitim mjernim metodama i postupcima. Također, opisane su tehnologije izrade solarnih ćelija od tankih filmova silicija, koje se danas najviše koriste. Nadalje, u radu je dat opis temeljnih karakteristika jednoslojnih solarnih ćelija i postupaka karakterizacije ćelija kroz slojeve strukture, kao i njihovo modeliranje korištenjem računalnog simulacijskog programa AMPS-1D. Svi postavljeni modeli u ovom radu temelje se na jednoslojnoj pin strukturi, sa jednim ili više aktivnih slojeva, kako bi se rezultati dobiveni proračunom mogli usporediti s ostalim rezultatima objavljenim u relevantnoj literaturi. Korišteni su modeli pin ćelije s jednim homogenim aktivnim slojem kao i modeli s višeslojnim homogenim aktivnim slojevima, koji, zapravo, opisuju nehomogenu strukturu u slučaju postojanja aktivnih slojeva većih debljina. Kroz ukupno osam grupa simulacija opisane su izlazne električne karakteristike modeliranih struktura osvijetljenih solarnih ćelija čiji su aktivni slojevi izrađeni od amorfnog silicija, amorfno-nanokristaliničnog silicija i nanokristaliničnog/mikro-kristaliničnog silicija. Promjenom optičkih i električnih parametara slojeva, ulaznih i graničnih uvjeta, kao i mijenjanjem količine primjesa i nečistoća u slojevima ćelija, izračunima su dobivene matrice podataka električnih parametara solarne ćelije. Prije svega, razmotrene su strujno-naponske karakteristike modeliranih struktura, faktor popunjenosti i efikasnost solarne ćelije. Podaci su opisani i predočeni grafički, a u zaključim razmatranjima je dana je analiza rezultata simulacija i proračuna. Predmetnim znanstvenim radom ostvarene su sve postavke hipoteze uključivo i očekivani izvorni znanstveni doprinos.The composite a-nc-Si:H thin films have been the subject of intense research for variety of applications due to their unique optical and electrical properties. Out of the many applications silicon thin films are used in thin layer transistors, tunable photo-diodes, and potential applications of composite silicon thin films are in third generation photovoltaic. First benefit of using a-nc-Si:H concerning optical properties. The optical gap of amorphous-nano-crystalline thin film materials can be adjusted in wide range with variation of size distribution of individual crystal sizes and the crystalline to amorphous fraction. The nano-crystals remain as individual in amorphous matrix enabling quantum size effects related to small dimensions of crystals. Evaluation of the optical properties and structural analysis of thin silicon samples showed that the spectral distribution of the absorption coefficient, in a wide range of crystal to amorphous fractions, can be maintained close to pure amorphous silicon in the visible part of the spectrum and showed square dependence on the photon energy. The average optical gap was larger for smaller nano-crystals and a higher crystal fraction Xc just confirming the quantum size effects that correspond to quantum dots. The most efficient thin film production techniques were also described: PECVD - Plasma-enhanced chemical vapor deposition, HWCVD - Hot Wire Chemical Vapor Deposition and some others. Described samples of amorphous and amorphous-nano-crystalline thin films with a thickness between 100 and 200 nm were deposited by the PECVD method using radio frequency glow discharge in a capacitive coupled parallel plate reactor. The High-Resolution Electron Microscopy (HRTEM) measurements were performed in a JEOL JEM-2010F transmission and scanning electron microscope (TEM/STEM) for evaluation of structural properties in ordered domains. The size distribution was estimated after software image processing in the reciprocal space using Bragg masks in the Digital Micrographs software. The individual sizes of the nanocrystals were approximated as spheres with a circular projection. Silicon thin films samples described in this work in process of determination are used in composite form, which is primarily characterized by the crystal fraction Xc and crystal grains sizes. It is necessary to understand effects of complex micro structural features on the overall electrical properties of thin films. The resistance and capacitance of crystals grains and grain boundaries, which is frequency and temperature dependent are evaluated from IS spectra. This technique for determination of the starting values for the basic equivalent electrical circuit were used in the fitting procedure of experimental impedance data with simulated data in order to select most appropriate equivalent circuit. This technique enables to separate the real and imaginary component of the complex impedance and related parameters, and hence provides information of the structure-property relationship in the rated samples. In present work a semi conducting silicon properties, hetero-junctions and photo effect in intrinsic silicon thin films have also been studied, and optical generation and recombination of free carriers and transport model had been investigated. Better transport model HQD is suggested hence to structural nature of described and modelled composite silicon layers. Therefore, bases physical principles of simple silicon solar cells with accent to amorphous-nanocrystalline layers as permissible composite material for high efficiency solar cells called third generation layers have been studied. Thin film characterisation techniques were characterised revealing structural, optical and electrical properties. In order to determine electrical characteristics a bases principles of pin structure solar cells have been carried out with one dimensional computer modelling programme AMPS-1D (Analysis of Microelectronic and Photonic Structures). Programme was primary used for parameter calculations of semiconductor devices, diodes, microelectronic and photonic structures. All suggested solar cell models are based to simple pin structure in order to compare simulation results with others in references. Computer modelling programme allows solar cell parameter calculations and structure design simulations. By varying significant ranges of solar cells parameters such as: illumination spectra, photon flux, absorption coefficient, boundary conditions, front and back contact parameter, general silicon layer parameters as doping and free carrier concentrations, mobility, gap state defect distribution, I-V characteristic, fill factor (FF), and efficiency () of solar cell can be determinate. In this work eight (8) simulation groups are carried out with intrinsic layers of amorphous (a-Si:H), amorphous-nano-crystalline (a-nc-Si:H) and micro-crystalline (c-Si:H) materials. Suggested model performed calculations in homogenous absorber layer, two-phase and absorber-multilayer solar cell structures. Solar cell with homogenous absorber layer showed efficiency of almost 14% at thickness of 1m. Calculated efficiency of absorber-multilayer solar cell structure of thickness 500 nm in final simulation reached 12,3%. All calculated solar cells data of all modelled structures were graphically presented and discussed

Uncertainty of Displacement Determination of the Valve in the Steam Turbine Control System

Zbog osobite važnosti vrijednosti pomaka glavnih regulacijskih ventila u regulacijskom sustavu parne turbine, nužno je potreban kvalitetan mjeriteljski nadzor. Složenim sustavom koji se sastoji od mjernog pretvornika, sustava za pretvorbu strujnog u naponski signal i industrijskog prijenosnog računala sa A/D karticom, te softverom za mjerenje i obradu podataka, vrši se mjeriteljski nadzor. Pripadna mjerna nesigurnost određuje se uzimanjem u obzir svih fizikalnih utjecaja i zakonitosti koje vladaju za vrijeme mjerenja pomaka u konkretnoj izvedbi jednog takvog parnog ventila. Nakon analize zakonitosti eksperimentalno i analitički procijenjuju se pojedinačni doprinosi ukupnoj nesigurnosti u svim radnim uvjetima koristeći se međunarodno prihvaćenim ISO preporukama. U radu se primjenjuju znanstvene metode po preporukama ISO organizacije pri razradi općih algoritama u slučaju djelovanja utjecajnih veličina, izračuna raznih doprinosa ukupne nesigurnosti koristeći matematički aparat i računske metode za njeno iskazivanje. Kritičkom analizom i bogatim mjeriteljskim iskustvom pripadne mjerne nesigurnosti raznih utjecajnih faktora uzete su sa najvećim mogućim faktorima proširenja zbog povećanja pouzdanosti. Na osnovu prikazanih znanstvenih postavki, pripadnih algoritama i računskih metoda korištenih u ovoj radnji, iskazivanje nesigurnosti pomaka ventila u regulacijskom sustavu parne turbine može poslužiti kao model šire primjene, u različitim drugim postupcima procjenjivanja nesigurnosti složenih mjernih sustava, te prilikom mjerenja drugih fizikalnih veličina također bitnih u analizi pouzdanosti i stabilnosti sustava regulacije parne turbine, kao što su zakretaj krila regulacijskog servomotora, tlak impulsnog ulja regulacijskih elektroničko-hidrauličkih pretvarača, ili drugih fizikalnih veličina nevezano uz regulacijski sustav parne turbine.The most important thing in governing system of steam turbine is the last chain in system, a steam valve. Because of meaning in order of stability, security and the working conditions of steam valve must be covered by supervising during phase of construction, manufacturing and commissioning. Measuring movement of steam valve in governing system of steam turbine is made by means of movement transducer, current to voltage converter and convenient software in applicable computer system with integrated A/D converter card. Measuring uncertainty of measuring result is occupied with all influence and physical laws during measuring procedure in real case. In procedure that follows the single uncertainties influences to summary measuring uncertainty are under analytic and experimental critics recommended and supervised by ISO institution. Uncertainty of measuring system which can occur in system causing by lots of influence factors will be performed and described in master work by means of following the guide lines of standards which are accepted and edited by distinguish ISO and others international institutions. By means of critics analyse and rich measuring experience given uncertainties are taken with great security extended factors in order to increase the certainty. Helped by scientific methods, issued algorithms and calculation methods performed in this work, uncertainty of displacement determination of the valve in the steam turbine control system can be used as model useful for other cases, in process of determination of uncertainties of different procedures and others physical values. That can be value of twisted angle of hydraulic servomotor, oil pressure of Electro hydraulic converters in steam turbine governing systems, or all others physical value out of steam turbine governing system

Modelling of electric characteristics of the photovoltaic amorphous-nanocrystalline silicon cell

U radu su opisana poluvodička svojstva silicija, hetero-spojevi silicija, istražen je foto-naponski efekt u intrinzičnom sloju, odnosno, generacija i rekombinacija slobodnih nosioca naboja. Opisane su fizikalne osnove jednoslojnih solarnih ćelija izrađenih od silicija, a predočen je amorfno-nanokristalinični silicij kao vrlo značajni kompozitni poluvodički materijal za izradu foto-naponskih ćelija visoke efikasnosti, takozvane solarne ćelije treće generacije. Navedene su strukturne, optičke i električne karakteristike tankih nc-Si:H filmova ustanovljenih različitim mjernim metodama i postupcima. Također, opisane su tehnologije izrade solarnih ćelija od tankih filmova silicija, koje se danas najviše koriste. Nadalje, u radu je dat opis temeljnih karakteristika jednoslojnih solarnih ćelija i postupaka karakterizacije ćelija kroz slojeve strukture, kao i njihovo modeliranje korištenjem računalnog simulacijskog programa AMPS-1D. Svi postavljeni modeli u ovom radu temelje se na jednoslojnoj pin strukturi, sa jednim ili više aktivnih slojeva, kako bi se rezultati dobiveni proračunom mogli usporediti s ostalim rezultatima objavljenim u relevantnoj literaturi. Korišteni su modeli pin ćelije s jednim homogenim aktivnim slojem kao i modeli s višeslojnim homogenim aktivnim slojevima, koji, zapravo, opisuju nehomogenu strukturu u slučaju postojanja aktivnih slojeva većih debljina. Kroz ukupno osam grupa simulacija opisane su izlazne električne karakteristike modeliranih struktura osvijetljenih solarnih ćelija čiji su aktivni slojevi izrađeni od amorfnog silicija, amorfno-nanokristaliničnog silicija i nanokristaliničnog/mikro-kristaliničnog silicija. Promjenom optičkih i električnih parametara slojeva, ulaznih i graničnih uvjeta, kao i mijenjanjem količine primjesa i nečistoća u slojevima ćelija, izračunima su dobivene matrice podataka električnih parametara solarne ćelije. Prije svega, razmotrene su strujno-naponske karakteristike modeliranih struktura, faktor popunjenosti i efikasnost solarne ćelije. Podaci su opisani i predočeni grafički, a u zaključim razmatranjima je dana je analiza rezultata simulacija i proračuna. Predmetnim znanstvenim radom ostvarene su sve postavke hipoteze uključivo i očekivani izvorni znanstveni doprinos.The composite a-nc-Si:H thin films have been the subject of intense research for variety of applications due to their unique optical and electrical properties. Out of the many applications silicon thin films are used in thin layer transistors, tunable photo-diodes, and potential applications of composite silicon thin films are in third generation photovoltaic. First benefit of using a-nc-Si:H concerning optical properties. The optical gap of amorphous-nano-crystalline thin film materials can be adjusted in wide range with variation of size distribution of individual crystal sizes and the crystalline to amorphous fraction. The nano-crystals remain as individual in amorphous matrix enabling quantum size effects related to small dimensions of crystals. Evaluation of the optical properties and structural analysis of thin silicon samples showed that the spectral distribution of the absorption coefficient, in a wide range of crystal to amorphous fractions, can be maintained close to pure amorphous silicon in the visible part of the spectrum and showed square dependence on the photon energy. The average optical gap was larger for smaller nano-crystals and a higher crystal fraction Xc just confirming the quantum size effects that correspond to quantum dots. The most efficient thin film production techniques were also described: PECVD - Plasma-enhanced chemical vapor deposition, HWCVD - Hot Wire Chemical Vapor Deposition and some others. Described samples of amorphous and amorphous-nano-crystalline thin films with a thickness between 100 and 200 nm were deposited by the PECVD method using radio frequency glow discharge in a capacitive coupled parallel plate reactor. The High-Resolution Electron Microscopy (HRTEM) measurements were performed in a JEOL JEM-2010F transmission and scanning electron microscope (TEM/STEM) for evaluation of structural properties in ordered domains. The size distribution was estimated after software image processing in the reciprocal space using Bragg masks in the Digital Micrographs software. The individual sizes of the nanocrystals were approximated as spheres with a circular projection. Silicon thin films samples described in this work in process of determination are used in composite form, which is primarily characterized by the crystal fraction Xc and crystal grains sizes. It is necessary to understand effects of complex micro structural features on the overall electrical properties of thin films. The resistance and capacitance of crystals grains and grain boundaries, which is frequency and temperature dependent are evaluated from IS spectra. This technique for determination of the starting values for the basic equivalent electrical circuit were used in the fitting procedure of experimental impedance data with simulated data in order to select most appropriate equivalent circuit. This technique enables to separate the real and imaginary component of the complex impedance and related parameters, and hence provides information of the structure-property relationship in the rated samples. In present work a semi conducting silicon properties, hetero-junctions and photo effect in intrinsic silicon thin films have also been studied, and optical generation and recombination of free carriers and transport model had been investigated. Better transport model HQD is suggested hence to structural nature of described and modelled composite silicon layers. Therefore, bases physical principles of simple silicon solar cells with accent to amorphous-nanocrystalline layers as permissible composite material for high efficiency solar cells called third generation layers have been studied. Thin film characterisation techniques were characterised revealing structural, optical and electrical properties. In order to determine electrical characteristics a bases principles of pin structure solar cells have been carried out with one dimensional computer modelling programme AMPS-1D (Analysis of Microelectronic and Photonic Structures). Programme was primary used for parameter calculations of semiconductor devices, diodes, microelectronic and photonic structures. All suggested solar cell models are based to simple pin structure in order to compare simulation results with others in references. Computer modelling programme allows solar cell parameter calculations and structure design simulations. By varying significant ranges of solar cells parameters such as: illumination spectra, photon flux, absorption coefficient, boundary conditions, front and back contact parameter, general silicon layer parameters as doping and free carrier concentrations, mobility, gap state defect distribution, I-V characteristic, fill factor (FF), and efficiency () of solar cell can be determinate. In this work eight (8) simulation groups are carried out with intrinsic layers of amorphous (a-Si:H), amorphous-nano-crystalline (a-nc-Si:H) and micro-crystalline (c-Si:H) materials. Suggested model performed calculations in homogenous absorber layer, two-phase and absorber-multilayer solar cell structures. Solar cell with homogenous absorber layer showed efficiency of almost 14% at thickness of 1m. Calculated efficiency of absorber-multilayer solar cell structure of thickness 500 nm in final simulation reached 12,3%. All calculated solar cells data of all modelled structures were graphically presented and discussed

Design and Implementation of a Ball-Plate Control System and Python Script for Educational Purposes in STEM Technologies

This paper presents the process of designing, fabricating, assembling, programming and optimizing a prototype nonlinear mechatronic Ball-Plate System (BPS) as a laboratory platform for engineering education STEM. Due to the nonlinearity and complexity of BPS, the task presents challenges such as: (1) difficulty in controlling the stabilization of a particular position point, known as steady-state error, (2) position resolution, known as specific distance error, and (3) adverse environmental effects—light-shadow error, which is also discussed in this paper. The laboratory prototype BPS for education was designed, manufactured and installed at Karlovac University of Applied Sciences in the Department of Mechanical Engineering, Mechatronics program. The low-cost two-degree BPS uses a USB HD camera for computer vision as a feedback sensor and two DC servo motors as actuators. Due to control problems, an advanced block diagram of the control system is proposed and discussed. An open-source control system based on Python scripts, which allows the use of ready-made functions from the library, allows the color of the ball and the parameters of the PID controller to be changed, indirectly simplifying the control system and performing mathematical calculations directly. The authors will continue their research on this BPS mechatronic platform and control algorithms