3D DIGITIZATION OF FEATURELESS DENTAL MODELS USING CLOSE RANGE PHOTOGRAMMETRY AIDED BY NOISE BASED PATTERNS

Development and improvement of 3D digitizing systems provide for the ability to digitize a growing number of materials and geometrical forms of greater complexity. This paper presents the application of 3D digitizing system using close range photogrammetry on the upper jaw cast in plaster in order to obtain its 3D model. Because of the low visual characteristics of gypsum, such as color and texture, many questions arise about the possibility of applying this particular method to this type of physical models. In order to overcome bad visual properties of gypsum, this paper analyzes the possibility of the photogrammetry method application supported by the projected light texture which is based on patterns in the form of noise-obtained  mathematically modeled functions. In order to determine the selected image for light texture which gives the better results, an experiment was designed and carried out. Only two images were tested. One image is selected based on previous research and the other one was generated by the Matlab function for uniformly distributed random numbers. For validation and a comparative analysis of the results, an object of 3D digitization was generated with and without projected light texture. CAD inspection was applied for the analysis of the obtained 3D digitizing results. 3D model obtained by approved professional optical 3D scanner as a reference was used. The results in this paper confirm better accuracy of 3D models obtained with the use of light textures, but this approach requires additional hardware and setup adjustment for images acquisition

Supplementary data for article: Šegan, S. B.; Trifković, J.; Verbić, T.; Opsenica, D. M.; Zlatović, M.; Burnett, J.; Šolaja, B. A.; Milojković-Opsenica, D. Correlation between Structure, Retention, Property, and Activity of Biologically Relevant 1,7-Bis(Aminoalkyl)Diazachrysene Derivatives. Journal of Pharmaceutical and Biomedical Analysis 2013, 72, 231–239. https://doi.org/10.1016/j.jpba.2012.08.025

Supplementary material for: [https://doi.org/10.1016/j.jpba.2012.08.025]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/1555

Supplementary data for article: Šegan, S. B.; Trifković, J.; Verbić, T.; Opsenica, D. M.; Zlatović, M.; Burnett, J.; Šolaja, B. A.; Milojković-Opsenica, D. Correlation between Structure, Retention, Property, and Activity of Biologically Relevant 1,7-Bis(Aminoalkyl)Diazachrysene Derivatives. Journal of Pharmaceutical and Biomedical Analysis 2013, 72, 231–239. https://doi.org/10.1016/j.jpba.2012.08.025

Supplementary material for: [https://doi.org/10.1016/j.jpba.2012.08.025]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/1555

SWITCHING NOISE REDUCTION IN SYNCHRONOUS DIGITAL CIRCUITS BASED ON CLOCK SKEW SCHEDULING

Sinhrona vezja, sintetizirana s standardnimi orodji, povzročajo velike konice napajalnega toka zaradi velikega števila sočasnih preklopov ob aktivnem prehodu urinega signala. To lahko povzroča presluhe, lokalne padce napetosti in nihanja na napajalnih žicah. Pri izdelavi preciznih mešanih sistemov to prestavlja velik problem zaradi motenj v delovanju nizkošumne analogne elektronike, ki je integrirana skupaj z digitalnim procesorjem signalov. V takšnih sistemih digitalna vezja večinoma vsebujejo različne filtre, pogosto z velikimi podatkovnimi besedami z dolžino preko 32 ali več bitov. Po drugi strani je hitrost pretoka obdelanih podatkov relativno nizka zaradi fizičnih omejitev analogne elektronike in senzorjev. V velikem številu sistemov na osnovi kemičnih ali elektro-mehanskih senzorjev ( MEMS) je izhodna pasovna širina podatkov z decimacijo omejena do ~150 Hz. Posledica tega je zelo veliko razmerje med amplitudo konice napajalnega toka in povprečno porabo digitalnega vezja, kar prestavlja lepo možnost za zmanjševanje preklopnega šuma na osnovi razporejanja urinega signala. Orodja za sintezo v tem smislu ne nudijo skoraj nobene podpore, saj so v celoti usmerjena v optimizacijo hitrosti, porabe moči in površine vezij. Naše delo je zato usmerjeno v zmanjševanje konic napajalnega toka z dodatnimi ukrepi, ki jih lahko uporabimo ob sodelovanju s standardnimi orodji za sintezo digitalnih vezij. V uvodnem poglavju je vključena kratka prestavitev znanih metod za odpravljanje preklopnega šuma. Prikazane prednosti in slabosti so odvisne od ciljev katerim sledimo pri izdelavi določenega sistema. V našem delu izhajamo iz predpostavke, da je hitrost obdelave signalov manj pomembna kot preklopni šum, ki nastaja zaradi istočasnih preklopov. Prav tako se omejimo izključno na tehnologijo CMOS, ker pri nizki hitrosti obdelave signalov omogoča najmanjšo porabo moči. V teh okoliščinah se najbolje izkaže metoda zamikanja urinega signala, kateri posvetimo pozornost v nadaljevanju poglavja. Prikazana problematika se izraža predvsem v potrebi po velikem številu zakasnilnih elementov in velikem številu potencialnih časovnih kršitev. V drugem poglavju podrobneje predstavimo zamikanje urinega signala in predlagamo rešitve prikazanih problemov. Za praktično uporabo je potrebno najprej rešiti problem kopičenja zakasnilnih celic, ki povzročajo povečanje porabe moči. Rešitev omogoča uporaba gonilnih celic signala ure v notranjosti registrov. Pri serijski razporeditvi signala ure vemo, da je signal na izhodu gonilnika obremenjen samo z enim vhodom (v naslednji, serijsko krmiljeni register), tako da lahko gonilnik v notranjosti registra uporabimo tudi kot gonilnik signala ure za naslednji register. S takim krmiljenjem lokalnih signalov ure ne pokvarimo strmine urinega signala znotraj registrske celice, posledično pa izločimo vse zunanje gonilnike ure, ki sicer lahko predstavljajo tudi do 30% porabe moči vezja. Za odpravljanje časovnih kršitev v vezju, ki nastanejo zaradi serijske razporeditve urinega signala, uporabimo latenčne registre, ki zakasnijo izhodni podatek za polovico periode ure. Ker taki registri porabijo več moči od navadnih registrov je smiselno njihovo število zmanjšati na najmanjše možno. Glavni namen tega dela je zato optimizacija števila latenčnih registrov ob predpostavki, da signal ure potuje serijsko v eni ali v večjem številu vej in pri tem zagotavlja sinhrono delovanje vezja brez časovnih kršitev. V tretjem poglavju je opisana optimizacija razporeditve urinega signala, ki temelji na minimalni uporabi latenčnih registrov. Za primerno matematično obdelavo je najprej analiziran matematični model sinhronega digitalnega vezja. Nato so predstavljene razne metode za optimalno razporeditev urinega signala. Predlagani optimizacijski problem je zaradi svoje specifičnosti mogoče prevesti v zmanjševanje zgornje pasovne širine matrike sosednosti. Ta je dosti hitrejši od klasičnih načinov, ker ni potrebno računanje časovnih razmer ob vsaki iteraciji. Iskanje rešitev smo dosegli na več načinov. V prvem načinu predlagamo algoritem za zmanjševanje pasovne širine na osnovi najmanjše stopnje vozlišča, tako da algoritem deluje samo na zgornji trikotni polovici matrike. Z uporabo genetskega algoritma dosežemo bistveno boljše rezultate na račun daljšega časa iskanja optimalne rešitve. V tretjem načinu smo iskali rešitev za sintezo s tehniko izklapljanja urinega signala na osnovi genetskega algoritma. Prestavljena je tudi uporaba algoritma z upoštevanjem znanih večcikličnih poti, s katerimi sprostimo časovne omejitve v vezju in je mogoče razporejanje urinega signala preko več ciklov. Na koncu je predstavljena tudi možnost uporabe predlagane metode pri vezjih z vgrajenimi testnimi strukturami. Četrto poglavje opisuje vključitev predlaganih algoritmov v standardna načrtovalska orodja. Uporaba načrtovalskih orodij je zelo pomembna, saj vsebujejo razne analizatorje za preverjanje časovne ustreznosti in funkcionalnosti vezja in omogočajo prenosljivost rezultatov. Posebne izvedbe celic smo zato ustrezno karakterizirali in vključili v knjižnice na osnovi standardnih zapisov, kot so HDL model v jeziku Verilog, časovni model NLDM in datoteka s fizičnim opisom LEF. Izdelali smo tudi generator matrike sosednosti, ki posreduje vse potrebne podatke za izvajanje optimizacijskih algoritmov. Pri običajni uporabi orodij namreč vsi podatki iz notranjih podatkovnih struktur niso dosegljivi in jih moramo dosegati posredno, s pomočjo ukaznega jezika TCL. V petem poglavju smo predstavili primerjalne rezultate tokovnih konic med različnimi sintezami. Naše metode smo preizkušali na nekaterih standardnih testnih vezjih ISCAS89 in ISCAS99. Eno izbrano vezje smo tudi podrobno analizirali ter opisali optimizacijski postopek z vmesnimi rezultati.Synchronous digital circuits implemented by standard synthesis tools are known to produce large current spikes due to simultaneous switching of registers, activated by the global clock. Voltage fluctuation on supply lines is of particular importance in high-precision mixed systems, where the need for low noise comes together with large data words, typically 32 bits or more. On the other hand, the processing speed is usually low, dictated by physical limitations of analog circuits and sensors. Many precision systems and data logging systems based on chemical or micro-electromechanical (MEMS) sensors have output data rates below 150 Hz, since the measurement results are highly filtered with the decimation process. As a consequence, the ratio of the peak supply current over the average value may be very large, indicating the feasibility of trading the circuit speed for the mitigation of switching noise. Synthesis tools put most effort into the optimization of speed, power, and area. When it comes to the switching noise minimization, they do not provide much support, and we have to apply additional design measures. In the first section we present the background and overview of known methods for switching noise reduction in digital circuits. With the assumption of low processing speed and low-power operation, we limit further discussion to the CMOS technology. In given circumstances, the serial clock distribution method is accepted as the most suitable to implement large switching noise reduction factors. The main problems, identified as power loss due to redundant switching, increased number of the registers, and potential timing violations are identified and left to be solved in the continuation of the work. A detailed description of serial clock distribution and suggested solutions for presented problems are shown in Section 2. In terms of power consumption, it is not economical to place delay buffers in front of every register cell. Considering that all clock buffers in the serial clock tree drive equal loads and that the loads are small, we propose to replace the clock delay buffers by register-internal clock buffers. The standard, minimum clock skew tree is therefore eliminated, enabling a large power saving (up to 30% power consumption of the circuit), in combination with the peak supply current reduction. If the clock period is not the limiting factor, then the timing solution can be assured by the application of shadowed registers. The data processing time is reduced to half of the clock period, while the other half remains to be used for serial clock distribution. Since shadowed registers consume more power and area than standard registers, we tend to replace as many shadowed registers with standard registers as possible, without compromising the timing constraints. Our aim is therefore to minimize the number of shadowed registers, provided that the clock is serially distributed in one or more branches without timing violations. In the third section we describe the optimization of the clock signal distribution based on the minimal use of shadowed registers. First, we introduce the general synchronous timing model for further mathematical processing. The given optimization problem is translated into the bandwidth reduction of the upper triangular part of the circuit adjacency matrix. This approach is much faster than other methods relying on iterative static timing analysis (STA). Still, heuristic approaches are required due to the algorithm complexity. In the continuation we investigate the bandwidth reduction in three directions. In the first approach we apply the minimum out-degree reordering, which turns out to be applicable only to small circuits with up to ~50 nodes. Better results, at the expense of longer computation times, are obtained with the genetic algorithm (GA) used in the second approach. Finally, in the third approach we upgrade the genetic algorithm to implement the serial clock distribution in combination with the gated clock synthesis. All presented algorithms are supplemented with necessary steps to accept timing relaxations given by the known multi-cycle. The section ends with the discussion of compatibility issues related to the serial clock distribution in the design-for-test (DFT) environment. The integration of the presented methods with standard design tools is presented in Section four. This important step puts to work various analyzers for circuit timing and functionality verification. Nonstandard cells are therefore characterized and included in the standard library, using common descriptions, such as Verilog HDL model, NLDM time model and LEF. With the help of standard design tools, we also create different data matrices containing parameters for the proposed optimization algorithms. In the fifth section, we present comparative results of supply current spike simulations in different synthesis cases. Our optimization methods have been verified on several standard test circuits from the ISCAS89 and ISCAS99 family. Detailed circuit analysis with intermediate results of one selected circuit is presented for illustration

Chemical selectivity and sensitivity of a 16-channel electronic nose for trace vapour detection

Good chemical selectivity of sensors for detecting vapour traces of targeted molecules is vital to reliable detection systems for explosives and other harmful materials. We present the design, construction and measurements of the electronic response of a 16 channel electronic nose based on 16 differential microcapacitors, which were surface-functionalized by different silanes. The e-nose detects less than 1 molecule of TNT out of 10$^{+12}$ N$_2$ molecules in a carrier gas in 1 s. Differently silanized sensors give different responses to different molecules. Electronic responses are presented for TNT, RDX, DNT, H$_2$S, HCN, FeS, NH$_3$, propane, methanol, acetone, ethanol, methane, toluene and water. We consider the number density of these molecules and find that silane surfaces show extreme affinity for attracting molecules of TNT, DNT and RDX. The probability to bind these molecules and form a surface-adsorbate is typically 10$^{+7}$ times larger than the probability to bind water molecules, for example. We present a matrix of responses of differently functionalized microcapacitors and we propose that chemical selectivity of multichannel e-nose could be enhanced by using artificial intelligence deep learning methods

Sensitivity comparison of vapor trace detection of explosives based on chemo-mechanical sensing with optical detection and capacitive sensing with electronic detection

The article offers a comparison of the sensitivities for vapour trace detection of Trinitrotoluene (TNT) explosives of two different sensor systems: a chemo-mechanical sensor based on chemically modified Atomic Force Microscope (AFM) cantilevers based on Micro Electro Mechanical System (MEMS) technology with optical detection (CMO), and a miniature system based on capacitive detection of chemically functionalized planar capacitors with interdigitated electrodes with a comb-like structure with electronic detection (CE). In both cases (either CMO or CE), the sensor surfaces are chemically functionalized with a layer of APhS (trimethoxyphenylsilane) molecules, which give the strongest sensor response for TNT. The construction and calibration of a vapour generator is also presented. The measurements of the sensor response to TNT are performed under equal conditions for both systems, and the results show that CE system with ultrasensitive electronics is far superior to optical detection using MEMS. Using CMO system, we can detect 300 molecules of TNT in 10$^{+12}$ molecules of N$_2$ carrier gas, whereas the CE system can detect three molecules of TNT in 10$^{+12}$ molecules of carrier N$_2$

Correlation between structure, retention, property, and activity of biologically relevant 1,7-bis(aminoalkyl)diazachrysene derivatives

The physicochemical properties, retention parameters (R-M(0)), partition coefficients (log P-OW), and pK(a) values for a series of thirteen 1,7-bis(aminoalkyl) diazachrysene (1,7-DAAC) derivatives were determined in order to reveal the characteristics responsible for their biological behavior. The investigated compounds inhibit three unrelated pathogens (the Botulinum neurotoxin serotype A light chain (BoNT/A LC), Plasmodium falciparum malaria, and Ebola filovirus) via three different mechanisms of action. To determine the most influential factors governing the retention and activities of the investigated diazachrysenes, R-M(0), log P-OW, and biological activity values were correlated with 2D and 3D molecular descriptors, using a partial least squares regression. The resulting quantitative structure-retention (property) relationships indicate the importance of descriptors related to the hydrophobicity of the molecules (e.g., predicted partition coefficients and hydrophobic surface area). Quantitative structure-activity relationship models for describing biological activity against the BoNT/A LC and malarial strains also include overall compound polarity, electron density distribution, and proton donor/acceptor potential. Furthermore, models for Ebola filovirus inhibition are presented qualitatively to provide insights into parameters that may contribute to the compounds' antiviral activities. Overall, the models form the basis for selecting structural features that significantly affect the compound's absorption, distribution, metabolism, excretion, and toxicity profiles.Supplementary material: [http://cherry.chem.bg.ac.rs/handle/123456789/3477

Improving the chemical selectivity of an electronic nose to TNT, DNT and RDX using machine learning

We used a 16-channel e-nose demonstrator based on micro-capacitive sensors with functionalized surfaces to measure the response of 30 different sensors to the vapours from 11 different substances, including the explosives 1,3,5-trinitro-1,3,5-triazinane (RDX), 1-methyl-2,4-dinitrobenzene (DNT) and 2-methyl-1,3,5-trinitrobenzene (TNT). A classification model was developed using the Random Forest machine-learning algorithm and trained the models on a set of signals, where the concentration and flow of a selected single vapour were varied independently. It is demonstrated that our classification models are successful in recognizing the signal pattern of different sets of substances. An excellent accuracy of 96% was achieved for identifying the explosives from among the other substances. These experiments clearly demonstrate that the silane monolayers used in our sensors as receptor layers are particularly well suited to selecting and recognizing TNT and similar types of explosives from among other substances