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Papers by Gundars Zalcmanis

publication.editionName, 2016

After the substantial number of fatalities in road traffic increase with the start of icy 2014-20... more After the substantial number of fatalities in road traffic increase with the start of icy 2014-2015 winter conditions in Latvia drivers have been offered complimentary winter driving training. Having numerous drivers with their cars performing the same braking actions on restricted and safe test ground gave a good opportunity for evaluating driver skills and vehicle inuse tyre condition. Tyre age and tread depth were measured and driving instructions have been given to more than a thousand participants. Instrumented braking and manoeuvring measurements were made for thirty cars. The equipment included GPS receiver and decelerometer. Measurement results have been compared against physical observations and hints given by professional driving instructors. The comparison indicated that although the suggestions given to drivers by professional instructors clearly contribute to safer driving, the visual evaluation without measuring may lead to various errors in messages conveyed to drivers. The most questionable statement was about the influence of the vehicle mass on braking distance. The investigation did not show essential vehicle mass influence on tyre grip and correspondingly on braking characteristics. Tyre tread depth effect on braking performance demonstrated the relevance of technical requirements for winter tyres. The advantage of using public training for winter tyre in-use experiments is lower cost for getting tyre samples with various technical conditions. The disadvantages are the different skills of car owners, the need for individual instructions and the necessity to reckon with the training format, the limited choice of the testing variables and substandard conditioning of the road surface. The tests gave valuable information for further training sessions and coming winter tyre tests.

Performance parameters of different commercial diesel fuels is a subject of interest for fuel con... more Performance parameters of different commercial diesel fuels is a subject of interest for fuel consumers. Fuel retailer Neste recently introduced a new brand of WWFC 5th grade diesel fuel in Baltic market, consisting of diesel fuel and hydrotreated vegetable oil (HVO) blend. Fuel samples have been recently tested on chassis dynamometer, measuring wheel power and torque and in road conditions, measuring fuel consumption. Evaluation of fuel consumption and performance parameters in road or laboratory conditions may yield uncertain results due to complexity of modern automobile engine management and emission reduction systems. To better evaluate the combustion, fuel samples have been tested in modified CFR engine at various intake air pressure, temperature and compression ratio settings. Engine indicated performance parameters and combustion phasing of regular diesel fuel and diesel fuel-HVO blend are presented. Comparing to regular diesel fuel, fuel blend with HVO showed reduced apparent heat release rate (AHRR) during premixed combustion phase at low inlet air temperature and low compression ratio conditions, comparing to regular diesel fuel. Premixed combustion phase AHRR of diesel-HVO blend increased above AHRR of regular diesel fuel at higher inlet air temperature and higher compression ratio conditions. Diffusion controlled combustion phase AHRR of diesel-HVO blend increased above AHRR of regular diesel fuel at higher inlet air temperature, higher compression ratio conditions and supercharged air supply.

Metodiskie norādījumi paredzēti automobiļu transporta specialitātes maģistra studiju programmas s... more Metodiskie norādījumi paredzēti automobiļu transporta specialitātes maģistra studiju programmas studentiem RTU Transporta un mašīnzinību fakultātē

publication.editionName, 2012

Metodiskie norādījumi paredzēti kā palīgmateriāls projekta grafiskās daļas izstrādei automobiļu t... more Metodiskie norādījumi paredzēti kā palīgmateriāls projekta grafiskās daļas izstrādei automobiļu transporta specialitātes profesionālo bakalauru studiju programmas studentiem RTU Transporta un Mašīnzinību fakultātē

For decades much more attention has been devoted to emissions from transport vehicles and to usag... more For decades much more attention has been devoted to emissions from transport vehicles and to usage of various fuels and fuel blends for vehicle engine operation than to fuel consumption by this giving a chance for under-researched aftermarket products that allegedly reduce engine fuel consumption. The paper summarizes four fuel innovation product investigations commissioned to and carried out by the Department of Automotive Engineering of the Riga Technical University in a year scope. The innovative solutions offered by entrepreneurs contained a fossil diesel fuel treated by specific technology and three diesel fuel additives. The promoters of the products referred to pre-existing measurements showing 10 to 30 percent reduction of fuel consumption. Comparative experimental measurements using diesel fuel available in retail with and without usage of the proposed products have been done in laboratory conditions. The tests were performed on a stationary diesel generator RD2.0. Solid, repetitive results have been gained. The results did not confirm any significant positive effect of the products on engine brake specific fuel consumption. Factors affecting errors in this kind of product efficiency investigations for market promotion purposes and causes of positive effects from similar product applications in certain situations are discussed.

Procedia Computer Science, 2019

Different authorities and organizations are committed to reducing road traffic accidents, deaths ... more Different authorities and organizations are committed to reducing road traffic accidents, deaths and serious injuries. More and more stringent regulations are being introduced. Car manufacturers continuously improve design of the vehicles, introducing various innovations. One of the basic preconditions for realizing road traffic safety initiatives is compliance with existing legislation. This particularly applies to the vehicle systems and components that have the most significant impact on road safety. Unfortunately, to improve visibility on older cars, many car users in Eastern European countries, including Latvia, choose a primitive but unauthorized solution: installation of non-certified high intensity discharge (HID) lamps into the headlamps, which are designed for halogen bulbs. The goal of the research is to determine the extent to which illuminance levels are exceeded if inappropriate and uncertified HID lamps are installed in the car headlamps of different designs. In the course of the experiments there were tested reflection and projection headlamps of various designs intended to use with H1, H4 and H7 category halogen lamps and mostly used together with non-compliant HID bulbs.

Deviation of the real driving fuel consumption from the measured fuel economy given in vehicle sp... more Deviation of the real driving fuel consumption from the measured fuel economy given in vehicle specifications is a growing concern for certain groups of researchers, motorists and organizations. The motivations of the concern are from caring about the world environmental changes to very individual costs for motorists. The amount of deviation is blamed on vehicle manufacturers, car owners, service technicians and even poor country economies having more inferior roads, fuels and materials available. It is vital to differentiate between the fuel consumption variations caused by different driving conditions, driving styles, vehicle technical condition, fuel quality, car manufacturers increasing expertise of achieving or cheating low consumption test results and other factors. The paper shows vehicle driving energy requirement modeling for urban stop and go traffic at various average driving speeds. The modeling results are compared with real environment driving in the Latvian capital city Riga. Diverse driving conditions are modeled within urban driving speed limits. The car speed-time modeling function is reduced to simple and discrete constant acceleration and coast down events. The computer modeling and road test results show considerable variation of traction energy depending on the driving pattern. The paper forms an essential section in a more extensive research of fuel consumption in city driving.

Metodiskie norādījumi paredzēti automobiļu transporta specialitātes profesionālo bakalauru studij... more Metodiskie norādījumi paredzēti automobiļu transporta specialitātes profesionālo bakalauru studiju programmas studentiem RTU Transporta un mašīnzinību fakultātē

As the payload of trucks increases due to grow of road haulage and the haulers seeks to the utmos... more As the payload of trucks increases due to grow of road haulage and the haulers seeks to the utmost exploit tonnage of the truck there is necessity for complex of measurement system what provides determination of loads to all axis of vehicle and registration of parameters at any position of axis of vehicle or relief area of bearing of axis of vehicle during loading. There are developed load measurement systems with load sensors for two type of truck suspensions with pneumatic chamber and leaf-type springs.

At requests from several insurance companies, more than 100 advisory opinions and expert conclusi... more At requests from several insurance companies, more than 100 advisory opinions and expert conclusions on commercial vehicle driver's infringements in the field of compliance with the rules for working and resting times as well as for application of recording equipment (tachograph) in the local and international road haulage operations have been developed from 2008 to 2013. The aim of the research is to investigate the most common infringements of social provisions committed by commercial vehicle drivers involved in road transport accidents (RTA). The data included in this paper refer particularly to infringements committed by the drivers involved in driving vehicles which were registered in the Latvian registry. The paper summarizes and evaluates most common infringements of social legislation requirements for drivers involved in RTA in accordance with the Directive 2009/5/EC of the European Commission and the corresponding Latvian Cabinet of Ministers Regulations No.411 entered into force in 2008. Offences on drivers' allowed work and rest time periods, shortcomings at record keeping and inappropriate use of recording equipment (tachograph) by drivers of commercial vehicles are characterized in this paper based on findings and conclusions of in-depth case studies, advisory opinions and expert conclusions. The paper provides evaluation of infringements of social legislation requirements by their importance in relation to road safety, by type of recording equipment fitted to vehicles, by the quantity and type of offences committed simultaneously, as well as by other minor aspects. It was found that drivers have committed up to 10 different types of infringements at a single case. Most of the infringements discovered should be defined as very serious ones. Even in those cases when only one violation was found, in half of the cases it was defined as very serious infringement. The results of this paper will be further used in the next stage of research comparing the results obtained here with the data from regular roadside vehicle checks on the quantity and type of infringements of social legislation requirements.

Different organizations are committed to reducing deaths and serious injuries in road traffic. Th... more Different organizations are committed to reducing deaths and serious injuries in road traffic. Their activities must be guided by research to produce measurable results contributed in reducing casualties and making roads safer. This paper provides detailed information about the second stage of the study for an evaluation of social legislation infringements for international haulage truck drivers involved in severe road transport accidents. The data were obtained from original sources of information: from digital tachograph printouts, analog tachograph data record sheets and attestations of activities. The aim of the second research stage was to find out to which extent the drivers involved in severe road traffic accidents (hereinafter RTA) have committed infringements more often and in larger quantities compared to the data obtained from the vehicle and driver regular roadside checks, i.e. compared with the drivers not involved in RTA. The second task for the paper is to analyze infringements by type and by level of drivers' riskiness to be involved in the RTA. The obtained findings and conclusions of in-depth case studies have been compiled, processed, analyzed and systematized by severity, quantity and type of simultaneously committed offences, installed tachograph type and other parameters. The statistical data have been grouped, systematized and analyzed according to the aim of the research. Based on various sources of information, an analysis of infringements for international haulage truck drivers was made between the obtained average amount of infringements per severe RTA case and per regular roadside check. The results of the research state that the drivers involved in severe RTA have committed considerably more infringements before the actual RTA has happened. The most part of infringements directly or indirectly refers to the lack of rest time and increased driving or overall working hours. These infringements for international haulage truck drivers are referred to be as major factors contributing to drivers' fatigue and high accidents risk.

2022 IEEE 63th International Scientific Conference on Power and Electrical Engineering of Riga Technical University (RTUCON)

publication.editionName, 2016

publication.editionName, 2012

Procedia Computer Science, 2019

2022 IEEE 63th International Scientific Conference on Power and Electrical Engineering of Riga Technical University (RTUCON)