Medium access control protocol for visible light communication in vehicular communication networks

Recent achievements in the automotive industry related to lighting apparatuses include the use of LED or laser technology to illuminate the vehicle environment. This advancement resulted in greater energy efficiency and increased safety with selective illumination segments. A secondary effect was creating a new field for researchers in which they can utilize LED fast modulation using the Pulse Width Modulation (PWM) signal. Using LED to encode and transmit data is a relatively new and innovative concept. On the other field, there have been advancements in vehicular communication using radio frequency at 2.4 or 5GHz. This research focuses mainly on a field in which visible light augments or replaces radio frequency communication between vehicles. This research also investigates the effect of asymmetry on network performance using Visible Light Communication (VLC) in vehicular networks. Different types of asymmetry were defined and tested in real-world simulation experiments. Research results showed that asymmetry has a negative influence on network performance, though that effect is not significant. The main focus of the research is to develop a lightweight and new Media Access Control (MAC) protocol for VLC in vehicular networks. To develop a MAC protocol for VLC, special software was developed on top of the existing Network Simulation Environment (NSE). A new VLC MAC protocol for Vehicle to Vehicle (V2V) was benchmarked using a defined set of metrics. The benchmark was conducted as a set of designed simulation experiments against the referent IEEE 802.11b MAC protocol. Both protocols used a newly defined VLC-equipped vehicle model. Each simulation experiment depicted a specific network and traffic situation. The total number of scenarios was eleven. The last set of simulations was conducted in realworld scenarios on the virtual streets of Suffolk, VA, USA. Using defined metrics, the test showed that the new VLC MAC protocol for V2V is better than the referent protocol.Nedavna dostignuća u automobilskoj industriji koja se tiču opreme za osvjetljivanje uključuju korištenje LED ili laserskih rasvjetnih tijela za osvjetljivanje okoline. Ovime se postižu uštede u potrošnji energije kao i povećana sigurnost u prometu. LED rasvjeta je uniformnija od običnih žarulja tako da osvjetljenje bude ravnomjernije i preciznije. Obzirom da su LED selektivne moguće je odabrati segment ceste koji se želi osvijetliti. Upravo ta fleksibilnost LED otvara novi prostor za istraživače gdje mogu koristiti PWM signal za modulaciju podataka. PWM je poseban signal koji ima varijabilnu širinu pulsa na izlazu. Istraživači i znanstvenici mogu koristiti LED za kodiranje i prijenos podataka između automobila. Prednosti korištenja komunikacije u vidljivom dijelu elektro-magnetskog spektra (eng.VLC) je u činjenici da taj segment nije zaštićen licencama te je otvoren za slobodno korištenje. Osim toga, vidljivo, neintenzivno svjetlo nema biološki negativnih posljedica. Kod korištenja PWM signala za modulaciju, postojeći izlaz svjetla i njegova funkcija (osvjetljivanja ceste) nisu narušeni. Ljudsko oko ne može detektirati oscilacije tako visoke frekvencije (oko 5 kHz) S druge strane, komponente koje mogu primiti poslani signal su foto diode ili kamere. Kamere su već prisutne na modernom vozilu u obliku prednje kamere ili stražnje kamere za pomoć pri parkiranju. U svakom slučaju, tehnologija je već prisutna na modernom vozilu. Na drugom području, znanstvenici rade na komunikaciji između vozila koristeći radio valove niže frekvencije 2.4 ili 5 GHz. Komunikacija između automobila je predmet standardizacije i mnoge zemlje već propisuju pravila za obaveznu ugradnju opreme za takav oblik komunikacije. Prednost takvog koncepta je razmjena podatka; od onih za zabavu pa do kritičnih i sigurnosnih podataka npr. informacija o nadolazećem mjestu gdje se dogodila prometna nesreća. Ovo istraživanje se fokusira na proširenje ili zamjenu radio komunikacije sa komunikacijom koristeći vidljivi dio spektra (npr. LED i kamere). Jedan od glavnih nedostataka takvog koncepta je ne postojanje adekvatnog i specijaliziranog protokola za kontrolu pristupa mediju (eng. MAC). Drugi problem je nepoznati efekt asimetrije u VLC komunikaciji na performanse mrežne komunikacija. Ovo istraživanje je prepoznalo i klasificiralo različite tipove asimetrije. Svaki tip je testiran u sklopu simulacijskog eksperimenta u stvarnim scenarijima. Pokazalo se je da asimetrija negativno utječe na mrežne performanse, međutim taj efekt nije značajan jer uzrokuje manje od 0.5 % neuspješno poslanih poruka. Glavni fokus istraživanja je razvoj novog i pojednostavljenog MAC protokola za VLC komunikaciju između automobila. Kako bi se razvio novi MAC protokol nad VLC tehnologijom u prometnim mrežama, bilo je nužno napraviti i novu razvojnu okolinu koja se bazira na postojećim mrežnim simulatorima. Novi VLCMAC protokol za komunikaciju između automobila je testiran koristeći definirani set metrika. Testovi su napravljeni u obliku simulacijskih eksperimenata u kojima su uspored¯ivane performanse novog i referentnog protokola. Referentni protokol, u ovom istraživanju je IEEE 802.11b MAC protokol. U sklopu ovog rada definiran je i model vozila opremljen VLC tehnologijom. U simulacijskim eksperimentima je korišten isti model vozila za oba protokola. Za potrebe istraživanja je definirano jedanaest simulacijskih eksperimenata, svaki od njih opisuje specifične situacije u mrežnim komunikacijama kao i u prometu. Završni simulacijski scenariji uključuju okolinu iz stvarnosti, mreža ulica grada Suffolka, SAD. Osim stvarnih ulica, vozila su se kretala i razmjenjivala podatke koristeći mrežnu komunikaciju na kompletnom ISO/OSI mrežnom stogu sa zamijenjenim MAC podslojem. Razvojna okolina uključuje preciznu provjeru fizičkih karakteristika na razini putanje zrake svjetlosti. Ova preciznost je bila nužna kako bi simulacije bile što vjerodostojnije stvarnim sustavima. Obzirom da se radi o mnogo kalkulacija, obično računalo nije dostatno za izvođenje simulacijskih eksperimenata; zbog toga su se eksperimenti izvodili na klasteru računala Sveučilišta u Zagrebu. Koristeći definirane metrike, istraživanje je pokazalo kako je novi VLC MAC protokol za komunikaciju između automobila bolji od referentnog protokola.

Utjecaj raznih izvora ugljika na in vitro ukorjenjavanje višnje cv.Oblačinska

The effect of different carbon sources on in vitro rooting of sour cherry cv.Oblačinska was investigated at the Agricultural Institute Osijek, Croatia. Sour cherry cv. Oblačinska micropropagated shoots were rooted on half-strength Murashige and Skoog (MS) medium, supplemented with different types and concentrations of sugars, in order to determine the effects of sugar composition and concentration on in vitro rooting. The influence of four carbon sources, sucrose (SU), glucose (G), fructose (F) and sorbitol (SO) on in vitro rooting of sour cherry cv. Oblačinska was compared at 0, 20, 30, 40 and 50 g L⁻1 concentrations. Type and concentration of carbohydrates had a significant effect on rooting percentage, mean root number, mean root length and mean fresh and dry root weight. Among the various carbohydrates tested, the best rooting response was obtained with sucrose in terms of rooting frequency, number of roots and root length.Na Poljoprivrednom institutu Osijek istraživan je utjecaj različitih vrsta ugljikohidrata na in vitro ukorjenjivanje Oblačinske višnje. Razmnožene biljke su ukorijenjene na Murashige i Skoog podlozi (MS) s različitim vrstama i koncentracijama ugljikohidrata, s ciljem da se utvrdi njihov utjecaj na in vitro ukorjenjivanje. Četiri različita ugljikohidrata, saharoza, glukoza, fruktoza i sorbitol su uspoređivani u koncentracijama 0, 20, 30, 40 i 50 g L-1. Vrsta i koncentracija ugljikohidrata imale su znatan učinak na postotak ukorjenjivanja, broj korijenčića, dužinu korijenčića, svježu i suhu tvar korijena. Između testiranih ugljikohidrata najbolji rezultati ukorjenjivanja postignuti su sa saharozom, glede postotka ukorjenjivanja, broja korijenčića i dužine korijenčića

Effects of sodium hypochlorite /NaCIO/ and mercuric (II) chlorite /HgCI2/ on surface sterilization of Oblačinska sour cherry buds in in vitro culture

U kulturi in vitro vrlo je važno pronaći odgovarajuće sredstvo koje će ukloniti bakterije i gljivice iz biljnog tkiva i stanice prije unošenja na podlogu. Stoga je površinska sterilizacija vrlo važan korak u pripremanju eksplantata. U ovom radu istraživanje je rađeno na pupovima Oblačinske višnje klona OS. Istraživano je djelovanje natrijevog hipoklorita (NaClO) i živinog (II) klorida (HgCl₂) u različitim koncentracijama i dužini trajanja sterilizacije pupova. Pupovi su najprije sterilizirani sa 70% etanola, a nakon toga s NaClO koncentracije 1, 2 i 3% u trajanju od 20, 15 i 10 min te s HgCl₂ koncentracije 0.1, 0.5 i 1% u trajanju od 10, 5 i 2 min. Sterilizirani pupovi su inokulirani na hranjivu podlogu. Nakon mjesec dana utvrđen je broj kontaminiranih, propalih i zdravih biljčica. Najbolje rezultate pokazala je površinska sterilizacija sa 1% NaClO u trajanju od 20 min s 80% zdravih biljčica.To obtain in vitro culture it is very important to find a solvent for removing bacterial and fungi from explant tissue. Surface sterilization is the most important step in preparation of explants. In the present study research was conducted on sour cherry cv. Oblačinska višnja, clone OS. A comparison was made between sodium hypochlorite (NaOCl) and mercuric chloride (HgCl₂) with different times of buds sterilization. First, buds were sterilized with 70% of ethanol for few seconds and after that they were sterilized with sodium hypochlorite (concentration 1, 2, and 3%, for 20, 15 and 10 min.) and mercuric chlorite (concentration 0.1, 0.5 and 1%, for 10, 5 and 2 min.) Sterilized explants were inoculated on culture medium. After one month the number of contaminated, collapsed and healthy plants was determinate. The best results were obtained by surface sterilization with 1% NaOCl with exposure of 20 min, with 80% healthy, survival plants

Effects of sodium hypochlorite /NaCIO/ and mercuric (II) chlorite /HgCI2/ on surface sterilization of Oblačinska sour cherry buds in in vitro culture

U kulturi in vitro vrlo je važno pronaći odgovarajuće sredstvo koje će ukloniti bakterije i gljivice iz biljnog tkiva i stanice prije unošenja na podlogu. Stoga je površinska sterilizacija vrlo važan korak u pripremanju eksplantata. U ovom radu istraživanje je rađeno na pupovima Oblačinske višnje klona OS. Istraživano je djelovanje natrijevog hipoklorita (NaClO) i živinog (II) klorida (HgCl₂) u različitim koncentracijama i dužini trajanja sterilizacije pupova. Pupovi su najprije sterilizirani sa 70% etanola, a nakon toga s NaClO koncentracije 1, 2 i 3% u trajanju od 20, 15 i 10 min te s HgCl₂ koncentracije 0.1, 0.5 i 1% u trajanju od 10, 5 i 2 min. Sterilizirani pupovi su inokulirani na hranjivu podlogu. Nakon mjesec dana utvrđen je broj kontaminiranih, propalih i zdravih biljčica. Najbolje rezultate pokazala je površinska sterilizacija sa 1% NaClO u trajanju od 20 min s 80% zdravih biljčica.To obtain in vitro culture it is very important to find a solvent for removing bacterial and fungi from explant tissue. Surface sterilization is the most important step in preparation of explants. In the present study research was conducted on sour cherry cv. Oblačinska višnja, clone OS. A comparison was made between sodium hypochlorite (NaOCl) and mercuric chloride (HgCl₂) with different times of buds sterilization. First, buds were sterilized with 70% of ethanol for few seconds and after that they were sterilized with sodium hypochlorite (concentration 1, 2, and 3%, for 20, 15 and 10 min.) and mercuric chlorite (concentration 0.1, 0.5 and 1%, for 10, 5 and 2 min.) Sterilized explants were inoculated on culture medium. After one month the number of contaminated, collapsed and healthy plants was determinate. The best results were obtained by surface sterilization with 1% NaOCl with exposure of 20 min, with 80% healthy, survival plants

The Bitcoin Phenomenon Analysis

Bitcoin, the latest Internet phenomenon branded as a game-changer. It is a revolution in financial system and money creation mechanics which currently holds the market of almost 13 billion USD. At the same time, its inner working is presented as hard to understand but perfectly trustworthy and safe. This trust is what gives Bitcoin value, however due to its mystical creator and recent headlines with negative connotation, what to really make of it? - In this paper we try to explain the Bitcoin and present the latest related research to provide a discussion ab out its potential impact on economy, financial world and society

PROCESS APPROACH TO CREATING A COMPANY PERFORMANCE MODEL

Changed circumstances, new markets and strategies require constant improvement of enterprise performance measurement systems. Effective performance measurement is crucial for successful implementation of enterprise strategy, the development and survival in the modern economy. Today, the emphasis on the measurement of the scope of the enterprise, requiring a wide range in addition to financial and nonfinancial indicators also. Since a contemporary management of the organization involves management of its processes, the achievement of organization’s goals depends on the success of its processes. The success of the process is measured by using key performance indicators

Company anti-bribery management system

Corruption is one of most destructive and complex problems nowadays. Its results negatively influence business environment, political stability and level of standard. On global level corruption presents major barrier in international trade. Governments of many countries have passed national program for battling corruption. The total cost of fraud will be difficult to objectively assess, in particular, will be difficult to calculate the indirect damage caused by fraud. Some frauds will never be discovered. It is estimated that organisations around the world on average lose 5% of annual revenues to fraud. Small reduction in costs due to fraud can significantly increase profit of organisation. The International Organization for Standardization has developed standard ISO 37001 – Anti-bribery management systems. It’s the International Standard that allows organizations of all types to prevent, detect and address bribery by adopting an antibribery policy, appointing a person to oversee anti-bribery compliance, training, risk assessments and due diligence on projects and business associates, implementing financial and commercial controls, and instituting reporting and investigation procedures. Providing a globally recognized way to address a destructive criminal activity that turns over a trillion dollars of dirty money each year, ISO 37001 addresses one of the world’s most destructive and challenging issues head-on, and demonstrates a committed approach to stamping out corruption. Paper presents research on level of corruption in Bosnia and Herzegovina, comparison with level of corruption in other courtiers, as well as correlation with the global competitiveness index. Moreover, paper presents methodology for development and implementation of system for battel against corruption in companies. Research results bring new scientific facts and findings in battle against corruption and methodological process of implementation of system for battel against corruption in companies

Anti-Fraud Strategy

Fraud is not an individual problem, but rather, we deal with a systematic fraud, particularly in the public sector through the creation of a private monopoly over public sector. Therefore, the first step, which needs to be set in organization in order to develop an efficient system for fraud control is development of anti-fraud strategy. Anti-fraud strategy is based on a policy of integrity and zero tolerance for fraud. Under the fraud we imply: corruption, assets misappropriation and fraudulent statement. Fraudsters are in the organization and beyond. Factors influencing performing of fraud are: pressure, opportunity and rationalization. Costs incurred due to the fraud may be difficult to realistically consider. Battle against fraud is determined by political will, effective legislation and anti-fraudulent culture and strategy

The significance of serum thyroglobulin measurement before and after the treatment of toxic nodular goiter with 131I

Thyroglobulin is routinely used as tumor marker in follow upa of patients with toxic nodular goiter. The aim of this studya was to evaluate the role of thyroglobulin measurement prior to and after radioiodine therapy and to compare the results with the therapy outcome