Valentin Alexandru Stan

Dr. Valentin Alexandru Stan


Research Focus & Metrics

Academic Career Length

8Years (2019-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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1 October 2017
Verified
Conference Paper
Closed access
VIValentin Iordache
Valentin Iordache
RGRazvan Andrei Gheorghiu
Razvan Andrei Gheorghiu
MMMarius Minea
Marius Minea
ACAngel Ciprian Cormos
Angel Ciprian Cormos
Vehicle to infrastructure communications (V2I) are more and more common in nowadays Intelligent Transport Systems' applications dedicated to increasing safety and reducing driving stress, or to reducing environmental pollution. Telegrams exchanged between moving vehicles and road side units (RSUs) allow the delivery of updated information to traffic participants and gathering important data regarding the number of vehicles passing a certain section of a road, vehicle density on a road section, average speed etc. However, short-range radio communications, automatic handshaking / authentication are challenging features, especially when vehicles move with high velocity. Actual technologies include DSRC and IEEE 802.x standards, but sometimes these become crowded or saturated, preventing effective data exchange. Taking these into account, additional communications technologies such as Bluetooth and ZigBee have been field-tested to evaluate the possibility of supporting extended V2I messaging facilities. Results and recommendations are presented in the paper.

17 May 2019 in Energies
Verified
Journal Article
Open access
PDF file
Nicu BizonNicu Bizon
Nicu Bizon
VSValentin Alexandru Stan
Valentin Alexandru Stan
UCUPB-CEPETET Cormos
UPB-CEPETET Cormos
In this paper, a systematic analysis of seven control topologies is performed, based on three possible control variables of the power generated by the Fuel Cell (FC) system: the reference input of the controller for the FC boost converter, and the two reference inputs used by the air regulator and the fuel regulator. The FC system will generate power based on the Required-Power-Following (RPF) control mode in order to ensure the load demand, operating as the main energy source in an FC hybrid power system. The FC system will operate as a backup energy source in an FC renewable Hybrid Power System (by ensuring the lack of power on the DC bus, which is given by the load power minus the renewable power). Thus, power requested from the batteries’ stack will be almost zero during operation of the FC hybrid power system based on RPF-control mode. If the FC hybrid power system operates with a variable load demand, then the lack or excess of power on the DC bus will be dynamically ensured by the hybrid battery/ultracapacitor energy storage system for a safe transition of the FC system under the RPF-control mode. The RPF-control mode will ensure a fair comparison of the seven control topologies based on the same optimization function to improve the fuel savings. The main objective of this paper is to compare the fuel economy obtained by using each strategy under different load cycles in order to identify which is the best strategy operating across entire loading or the best switching strategy using two strategies: one strategy for high load and the other on the rest of the load range. Based on the preliminary results, the fuel consumption using these best strategies can be reduced by more than 15%, compared to commercial strategies.

3 June 2018 in Sensors
Verified
Journal Article
Open access
PDF file
RGRazvan Andrei Gheorghiu
Razvan Andrei Gheorghiu
VIValentin Iordache
Valentin Iordache
As road traffic conditions worsen due to the constantly increasing number of cars, traffic management systems are struggling to provide a suitable environment, by gathering all the relevant information from the road network. However, in most cases these are obtained via traffic detectors placed near road junctions, thus providing no information on the conditions in between. A large-scale sensor network using detectors on the majority of vehicles would certainly be capable of providing useful data, but has two major impediments: the equipment installed on the vehicles should be cheap enough (assuming the willingness of private car owners to be a part of the network) and be capable of transferring the required amount of data in due time, as the vehicle passes by the road side unit that acts as interface with the traffic management system. These restrictions reduce the number of technologies that can be used. In this article a series of comprehensive tests have been performed to evaluate the Bluetooth and ZigBee protocols for this purpose from many points of view: handshake time, static and dynamic data transfer (in laboratory conditions and in real traffic conditions). An assessment of the environmental conditions (during tests and probable to be encountered in real conditions) was also provided.

1 November 2021 in Sensors
Verified
Journal Article
Open access
PDF file
RGRazvan Andrei Gheorghiu
Razvan Andrei Gheorghiu
VIValentin Iordache
Valentin Iordache
UCUPB-CEPETET Cormos
UPB-CEPETET Cormos
As road traffic networks become more congested and information systems are implemented to manage traffic flows, real-time data gathering becomes increasingly important. Classic detectors are placed in one point of the network and are able to provide information only from that area. As useful as this is, it lacks the big picture of the routes the vehicles usually travel. There are applications developed to help individuals make their way into the road network, but these are no solutions that deal with the cause of traffic; rather, they counteract the effects. It becomes obvious that a proper management system, with knowledge of all the relevant aspects will better serve all travelers. The detection solution proposed in this paper is based on Bluetooth detectors. This system is able to match detected devices in the road network, filter the results, and generate a vehicle count that is proved to follow RADAR detection results.

7 June 2022 in Sensors
Verified
Journal Article
Open access
PDF file
RGRazvan Andrei Gheorghiu
Razvan Andrei Gheorghiu
FBFlorin Badau
Florin Badau
VIValentin Iordache
Valentin Iordache
Rail interlocking systems follow the progress of technology and train speeds. Nowadays, new systems are designed based on microcontrollers and reliable software, requiring many hours of testing to ensure their proper functionality and bug-free coding. However, in many countries, there are still older relay solutions implemented that are not envisaged to be upgraded in the near future partially due to costs but mainly due to the fact they function very well, being based on a highly reliable element: the relay. However, specialized maintenance personnel are becoming more difficult to find, so automation systems that check the proper relay functionality are a key element to ensure a longer lifetime of existing systems. In this article, the authors present a monitoring solution based on magnetic sensors that proved capable of provide reliable information about the relays, hence revealing the first step in a relay automated control system.

1 July 2017
Verified
Conference Paper
Closed access
RGRazvan Andrei Gheorghiu
Razvan Andrei Gheorghiu
VIValentin Iordache
Valentin Iordache
ACAngel Ciprian Cormos
Angel Ciprian Cormos
The key element in modern Intelligent Transport Systems is the communication between all the devices, as neither of them can run independently, but require interaction with other equipment. This is also true for vehicles: advances in autonomous vehicles field requires communications with other vehicles or infrastructure, in order for the vehicle to be aware of its environment. There are several technologies available for short/medium distance that are suitable for vehicular communications. The most used one for vehicle-to-vehicle is Dedicated Short Range Communication. However, in many applications this expensive technology is not necessary, especially when the key element is connection time, due to the reduced data quantity needed to be exchanged. In this paper we have performed analysis on Bluetooth, as the most common short distance communication technology, and we have tested the handshake time in noisy Wi-Fi environments.