Francisco Jose Lopez-Valdes

Dr. Francisco Jose Lopez-Valdes

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Research Focus & Metrics

Academic Career Length

9Years (2018-Present)

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

Representative Publications

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6 January 2021 in Journal of Ambient Intelligence and Humanized Computing
Verified
Journal Article
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HOHolman Ospina-Mateus
Holman Ospina-Mateus
LJLeonardo Augusto Quintana Jiménez
Leonardo Augusto Quintana Jiménez
FLFrancisco Jose Lopez-Valdes
Francisco Jose Lopez-Valdes
SGShyrle Berrio Garcia
Shyrle Berrio Garcia
LBLope H. Barrero
Lope H. Barrero
Shib Sankar SanaShib Sankar Sana
Shib Sankar Sana

8 September 2021 in Traffic Injury Prevention
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Journal Article
Closed access
HOHolman Ospina-Mateus
Holman Ospina-Mateus
LJLeonardo Quintana Jiménez
Leonardo Quintana Jiménez
FLFrancisco Jose Lopez-Valdes
Francisco Jose Lopez-Valdes
This study aimed to identify the association between behavioral factors and crashes of motorcycle taxi riders using the Motorcycle Rider Behavior Questionnaire (MRBQ).This study was a cross-section...

29 November 2021 in Applied Sciences
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Journal Article
Open access
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ÓJÓscar Juste-Lorente
Óscar Juste-Lorente
MMMARIO MAZA
MARIO MAZA
MPMathieu Piccand
Mathieu Piccand
FLFrancisco Jose Lopez-Valdes
Francisco Jose Lopez-Valdes
Oblique impacts of the helmet against the ground are the most frequent scenarios in real-world motorcycle crashes. The combination of two factors that largely affect the results of oblique impact tests are discussed in this work. This study aims to quantify the effect of the friction at the interface between the headform and the interior of a motorcycle helmet at different magnitudes of tangential velocity. The helmeted headform, with low friction and high friction surface of the headform, was dropped against three oblique anvils at different impact velocities resulting in three different magnitudes of the tangential velocity (3.27 m/s, 5.66 m/s, 8.08 m/s) with the same normal component of the impact velocity (5.66 m/s). Three impact directions (front, left-side and right-side) and three repetitions per impact condition were tested resulting in 54 impacts. Tangential velocity variation showed little effect on the linear acceleration results. On the contrary, the rotational results showed that the effect of the headform’s surface depends on the magnitude of the tangential velocity and on the impact direction. These results indicate that a combination of low friction with low tangential velocities may result into underprediction of the rotational headform variables that would not be representative of real-world conditions.

11 May 2021 in RAIRO - Operations Research
Verified
Journal Article
Closed access
PDF file
HOHolman Ospina-Mateus
Holman Ospina-Mateus
LJLeonardo Augusto Quintana Jiménez
Leonardo Augusto Quintana Jiménez
FLFrancisco Jose Lopez-Valdes
Francisco Jose Lopez-Valdes
Shib Sankar SanaShib Sankar Sana
Shib Sankar Sana
Motorcyclists account for more than 380 000 deaths annually worldwide from road traffic accidents. Motorcyclists are the most vulnerable road users worldwide to road safety (28% of global fatalities), together with cyclists and pedestrians. Approximately 80% of deaths are from low- or middle-income countries. Colombia has a rate of 9.7 deaths per 100 000 inhabitants, which places it 10th in the world. Motorcycles in Colombia correspond to 57% of the fleet and generate an average of 51% of fatalities per year. This study aims to identify significant factors of the environment, traffic volume, and infrastructure to predict the number of accidents per year focused only on motorcyclists. The prediction model used a negative binomial regression for the definition of a Safety Performance Function (SPF) for motorcyclists. In the second stage, Bayes’ empirical approach is implemented to identify motorcycle crash-prone road sections. The study is applied in Cartagena, one of the capital cities with more traffic crashes and motorcyclists dedicated to informal transportation (motorcycle taxi riders) in Colombia. The data of 2884 motorcycle crashes between 2016 and 2017 are analyzed. The proposed model identifies that crashes of motorcyclists per kilometer have significant factors such as the average volume of daily motorcyclist traffic, the number of accesses (intersections) per kilometer, commercial areas, and the type of road and it identifies 55 critical accident-prone sections. The research evidences coherent and consistent results with previous studies and requires effective countermeasures for the benefit of road safety for motorcyclists.

13 December 2018 in Traffic Injury Prevention
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Journal Article
Closed access
FLFrancisco Jose Lopez-Valdes
Francisco Jose Lopez-Valdes
KMKrystoffer Mroz
Krystoffer Mroz
AEAndre Eggers
Andre Eggers
BPBengt Pipkorn
Bengt Pipkorn
JMJulia Muehlbauer
Julia Muehlbauer
SPSteffen Peldschus
Steffen Peldschus
Objective: The goal of the study was to develop experimental chest loading conditions that would cause up to Abbreviated Injury Scale (AIS) 2 chest injuries in elderly occupants in moderate-speed frontal crashes. The new set of experimental data was also intended to be used in the benchmark of existing thoracic injury criteria in lower-speed collision conditions. Methods: Six male elderly (age >63) postmortem human subjects (PMHS) were exposed to a 35 km/h (nominal) frontal sled impact. The test fixture consisted of a rigid seat, rigid footrest, and cable seat back. Two restraint conditions (A and B) were compared. Occupants were restrained by a force-limited (2.5 kN [A] and 2 kN [B]) seat belt and a preinflated (16 kPa [A] and 11 kPa [B]; airbag). Condition B also incorporated increased seat friction. Matching sled tests were carried out with the THOR-M dummy. Infra-red telescoping rod for the assessment of chest compression (IRTRACC) readings were used to compute chest injury risk. PMHSs were exposed to a posttest injury assessment. Tests were carried out in 2 stages, using the outcome of the first one combined with a parametric study using the THUMS model to adjust the test conditions in the second. All procedures were approved by the relevant ethics board. Results: Restraint condition A resulted in an unexpected high number of rib fractures (fx; 10, 14, 15 fx). Under condition B, the adjustment of the relative airbag/occupant position combined with a lower airbag pressure and lower seat belt load limit resulted in a reduced pelvic excursion (85 vs. 110 mm), increased torso pitch and a substantially lower number of rib fractures (1, 0, 4 fx) as intended. Conclusions: The predicted risk of rib fractures provided by the THOR dummy using the Cmax and PC Score injury criteria were lower than the actual injuries observed in the PMHS tests (especially in restraint condition A). However, the THOR dummy was capable of discriminating between the 2 restraint scenarios. Similar results were obtained in the parametric study with the THUMS model.

11 February 2020 in International Journal of Injury Control and Safety Promotion
Verified
Journal Article
Closed access
HOHolman Ospina-Mateus
Holman Ospina-Mateus
LJLeonardo Augusto Quintana Jiménez
Leonardo Augusto Quintana Jiménez
FLFrancisco Jose Lopez-Valdes
Francisco Jose Lopez-Valdes
In 2016, Colombia’s position regarding motorcyclist fatalities per 100,000 inhabitants was tenth worldwide and second in South America. In the seven years from 2012-2018, the proportion of deceased and injured motorcyclists among all road users was 50%. To analyse the significant aspects of the accident rate of motorcyclists in Colombia from 2016 to 2018 and estimate cost social value of motorcycle-related deaths. The global numbers of fatalities and injuries were compared to the Colombian context. Descriptive and inferential statistics were conducted to explore the association of fatal trauma and motorcycle accidents. P values and odds ratios were calculated. Bogotá, Cali, and Medellín were the cities with the most accidents. The month, day, time, age of the victims, and climatic conditions had a statistically significant association with the fatal trauma. Most victims were between the ages of 20-29 years. Motorcycles were involved in more than 60% of accidents. The social cost of a life lost in a motorcycle accident was estimated at $2,418 million Colombian pesos (725,400 USD) per year. The establishment of countermeasures for the road safety of vulnerable users should focus on associated causal factors in order to develop strategies to effectively reduce the number of accidents.