Advanced search in
Research products
arrow_drop_down
Searching FieldsTerms
Any field
arrow_drop_down
includes
arrow_drop_down
Include:
2,053 Research products, page 1 of 206

  • Publications
  • Research data
  • 2022-2022
  • QA

10
arrow_drop_down
Date (most recent)
arrow_drop_down
  • Open Access English
    Authors: 
    M. Faisal Khan; M. Rizwan Khan; Atif Iqbal;
    Publisher: Elsevier Ltd
    Country: Qatar

    A squirrel cage induction machine (SCIM) when aggregated with relevant capacitances and a prime mover, acts as self-excited induction generator (SEIG). As it hosts energy conversion the parameters of SCIM have considerable impact on the power extraction capability of SEIG. An aspect which is missing from the available research on SEIGs is evaluation of the affects of its rotor's moment of inertia (J) and per-phase stator winding resistance (Rs) on performance indices. This work investigates the impacts of these factors on a SCIM's performance as series compensated, short shunt SEIG. The study considers two distinctly designed SCIMs, in terms of J and Rs, operated as SEIG. In order to simulate their performance a stationary reference frame dq model including non-linear saturation and cross coupling effects is developed and verified experimentally. Several key investigations based on series capacitance selection, losses and efficiency, on-load performance with different power factor loads, transient performance with load perturbation and variable speed operation are carried out. The study reveals that SEIG with high J and lower Rs gives considerably better performance than its counterpart. The conclusions reported in the study are important especially for standalone/off grid application of SEIGs. This publication was made possible by Qatar University Collaborative Research grant # [ QUCG-CENG-21/22-1 ] from the Qatar University . The statements made herein are solely the responsibility of the authors. The APC for the article is funded by the Qatar National Library, Doha, Qatar. Scopus

  • Open Access
    Authors: 
    Alaa Rahhal; Amr S Omar; Amer Aljundi; Mohamed Kasem; Ahmed Mahfouz; Sumaya Alyafei;
    Publisher: Elsevier BV

    Tachycardia in cardiogenic shock (CS) might reduce the cardiac output (CO) by decreasing the ventricular filling time. Nevertheless, heart rate (HR) control with agents that possess negative inotropy might decrease the CO. Therefore, controlling the tachycardia in the setting of CS remains controversial. We herein describe four cases of patients presenting with myocardial infarction complicated with CS that required rescue venoarterial extracorporeal membrane oxygenation (VA-ECMO) initiation. Tachycardia was present with HR ∼130-140 beats per minute after VA-ECMO initiation, and hence esmolol was infused continuously at a starting dose of 10-20 mcg/kg/min and titrated according to HR. With the use of esmolol to control the HR in the setting of CS supported with VA-ECMO, lactate cleared, and echocardiographic parameters improved, allowing the four cases to be successfully decannulated from ECMO. Our report indicates that short-acting beta-blocker could be safely used in the complex scenario of severe tachycardia while supported with VA-ECMO.

  • Authors: 
    Muhammad Ali Haidar; Stanley Ibeh; Zaynab Shakkour; Mohammad Amine Reslan; Judith Nwaiwu; Yomna Adel Moqidem; Georgio Sader; Rachel G Nickles; Ismail Babale; Aneese A Jaffa; +3 more
    Publisher: Bentham Science Publishers Ltd.

    : Microglia are the resident immune cells of the brain and play a crucial role in housekeeping and maintaining homeostasis of the brain microenvironment. Upon injury or disease, microglial cells become activated, at least partly, via signals initiated by injured neurons. Activated microglia, thereby, contribute to both neuroprotection and neuroinflammation. However, sustained microglial activation initiates a chronic neuroinflammatory response which can disturb neuronal health and disrupt communications between neurons and microglia. Thus, microglia-neuron crosstalk is critical in a healthy brain as well as during states of injury or disease. As most studies focus on how neurons and microglia act in isolation during neurotrauma, there is a need to understand the interplay between these cells in brain pathophysiology. This review highlights how neurons and microglia reciprocally communicate under physiological conditions and during brain injury and disease. Furthermore, the modes of microglia-neuron communication are exposed, focusing on cell-contact dependent signaling and communication by the secretion of soluble factors like cytokines and growth factors. In addition, how microglia-neuron interactions could exert either beneficial neurotrophic effects or pathologic proinflammatory responses are discussed. We further explore how aberrations in microglia-neuron crosstalk may be involved in central nervous system (CNS) anomalies, namely: traumatic brain injury (TBI), neurodegeneration, and ischemic stroke. A clear understanding of how the microglia-neuron crosstalk contributes to the pathogenesis of brain pathologies may offer novel therapeutic avenues of brain trauma treatment.

  • Open Access
    Authors: 
    Said Mahfoud; Aziz Derouich; Atif Iqbal; Najib El Ouanjli;
    Publisher: Elsevier BV
    Country: Qatar

    Direct Torque Control (DTC) presents an optimal solution to control the behaviors of the alternative motors, compared to other controls, because of several advantages offered by this technique, the speed overshoots, fluxes, and torque ripples remain the major factors which minimize the DTC robustness. The regulation speed in DTC is carried out by the classic Proportional Integrator Derivative (PID), which is known for its higher robustness in linear systems, except that in the case of non-linear systems, the PID controller gives poor reactions to variations in the system's parameters. The best solutions adopted in this situation are often based on optimization algorithms that generate the controller's gains in each period where there is an internal or external perturbation, adapting the behaviors of the PID against the system's nonlinearity. For that reason, this work is focused on the theoretical studies and experimental validation on dSPACE Board DS1104 of the new proposed approach based on PID speed regulation, optimized by the Ant Colony Optimization algorithm (ACO) for DTC, applied to both sides of the Doubly Fed Induction Motor (DFIM), to overcome the previous drawbacks cited at the beginning. The new combined ACO-DTC strategy has been studied for optimizing the gains of the PID controller by using a cost function such as Integral Square Error (ISE). The proposed approach is implemented on Matlab/Simulink to validate the objectives adopted by this strategy. The simulation and experimental results extracted from Matlab and ControlDesk have proved the efficiency of the proposed ACO-DTC with the system's nonlinearity, which attribute different enhancements in the global system performance. This publication was made possible by Qatar University Collaborative Research grant # [ QUCG-CENG-21/22-1 ] from the Qatar University. The statements made herein are solely the responsibility of the authors. The APC is funded by the Qatar NAtional Library, Qatar Scopus

  • Open Access
    Authors: 
    Ala Gouissem; Khalid Abualsaud; Elias Yaacoub; Tamer Khattab; Mohsen Guizani;
    Publisher: Institute of Electrical and Electronics Engineers (IEEE)
    Country: Qatar

    The internet of Things (IoT) is used to interconnect a massive number of heterogeneous resource constrained smart devices. This makes such networks exposed to various types of malicious attacks. In particular, jamming attacks are among the most common harmful attacks to IoT networks. Therefore, an anti jamming power allocation strategy is first proposed in this paper for health monitoring IoT networks by exploiting game theory to minimize the worst case jamming effect under multi channel fading. This strategy uses an iterative algorithm based on gradient descent to identify the Nash Equilibrium (NE) of the game. An artificial neural network model is also proposed to accelerate the convergence of the algorithm making it more suitable for IoT networks. Furthermore, novel data population, extension and balancing techniques are proposed to enhance the efficiency of the proposed strategy in combating jamming attacks even for network configurations that were never used in the training phase. In addition, time and spatial diversity are exploited using a heterogeneous iterative algorithm to enhance the security of the network.

  • Open Access English
    Authors: 
    Jecmen, Steven; Zhang, Hanrui; Liu, Ryan; Fang, Fei; Conitzer, Vincent; Shah, Nihar B.;
    Project: NSF | RI: Small: Designing Pref... (1814056), NSF | CIF: Medium: Foundations ... (1763734)

    Many scientific conferences employ a two-phase paper review process, where some papers are assigned additional reviewers after the initial reviews are submitted. Many conferences also design and run experiments on their paper review process, where some papers are assigned reviewers who provide reviews under an experimental condition. In this paper, we consider the question: how should reviewers be divided between phases or conditions in order to maximize total assignment similarity? We make several contributions towards answering this question. First, we prove that when the set of papers requiring additional review is unknown, a simplified variant of this problem is NP-hard. Second, we empirically show that across several datasets pertaining to real conference data, dividing reviewers between phases/conditions uniformly at random allows an assignment that is nearly as good as the oracle optimal assignment. This uniformly random choice is practical for both the two-phase and conference experiment design settings. Third, we provide explanations of this phenomenon by providing theoretical bounds on the suboptimality of this random strategy under certain natural conditions. From these easily-interpretable conditions, we provide actionable insights to conference program chairs about whether a random reviewer split is suitable for their conference.

  • Open Access
    Authors: 
    Ali, Kamran; Raja, Mahwish; Osman, Safa; Zulfiqar, Gulraiz; Janjua, Omer;
    Publisher: Springer Science and Business Media LLC
    Country: Qatar

    The number of people who are using prescribed medications is on the rise, largely due to an ageing population in the UK, but also because of early diagnosis and prompt medical management of a variety of conditions. Systemic medications may contribute to the development of oral side effects and translate into an increasing number of patients presenting in general dental practice settings. The aim of this paper is to provide an outline of oral side effects of systemic medications followed by a review of drug-associated oral ulcers (DAOUs). The paper also provides recommendations for early recognition and management of DAOUs in general dental practice settings, including referral to general medical practitioners and specialists in oral medicine.

  • Open Access
    Publisher: قناة الريان الفضائية
    Country: Qatar

    فيروس كورونا هل هو طاعون العصر الحديث؟ فيروسات كورونا فصيلة واسعة الانتشار ضيوف الحلقة: الدكتور/ عبداللطيف الخال - رئيس مركز الأمراض المعدية - مؤسسة حمد الطبية الدكتور/ هادي محمد ياسين - أستاذ كلية العلوم الصحية - جامعة قطر

  • Open Access English
    Authors: 
    Thomas Chatzikonstantinou; Lydia Scarfò; Christos Demosthenous; Jana Kotašková; Gloria Iacoboni; E. Minga; Dimitra Chammou; Georgios Karakatsoulis; Elisa Albi; Miguel Alcoceba; +119 more
    Country: Germany

    Abstract The use of novel small molecule inhibitors alone or in combination with anti-CD20 monoclonal antibodies for chronic lymphocytic leukemia (CLL) has raised a number of questions on efficacy, tolerability, long-term treatment adherence in patients with heterogeneous clinical features. To fill this gap, we designed a study focusing on treatment sequencing in patients with CLL in order to (i) compare the outcome of patients treated with chemoimmunotherapy (CIT) combinations in first-line versus those receiving Bruton's tyrosine kinase inhibitors (BTKi); (ii) characterize the efficacy and tolerability of venetoclax-based regimens; (ii) understand the impact of treatment sequencing when it comes to chemo-free options including venetoclax after BTKi and vice versa. Data from consecutive sets of patients diagnosed with CLL between 2000-2020 attended at 77 institutions affiliated with ERIC were collected and analyzed. Collected variables included: demographics, clinical stage at diagnosis, IGHV gene somatic hypermutation status; cytogenetic status for chromosomes 11q, 13q 17p and 12 determined by fluorescence in situ hybridization; TP53 gene mutation status; treatment; treatment response; discontinuation; reason for discontinuation; death. We included 9173 patients with a diagnosis of CLL who received at least one line of treatment. The median age at diagnosis was 67 years with a male:female ratio of 1.9. The median follow-up was 78 months (IQR, 48-120 months). Regarding novel targeted agents, 1860/9173 (20.2%) patients had received at least one line of treatment with BTKi (ibrutinib, n=1788; acalabrutinib, n=72) over the disease course; 631/9173 (6.9%) with venetoclax; and, 447/9173 (4.9%) with the PI3K inhibitor idelalisib. Seventy-nine patients were treated with both BTKi and venetoclax (59 BTKi followed by BCL2i, 20 vice versa). At last follow-up, 5870/9173 patients (64.0%) were alive, 3229/9173 (35.2%) died and 74/9173 (0.8%) were lost to follow-up. Patients treated with BTKi in first-line were enriched for TP53 aberrations [del(17p) 27.6%, TP53 mutation 26.3%] and unmutated IGHV genes (69%) and obtained an ORR of 87.7%. Of these, 136 (26.3%) discontinued treatment after a median of 1.2 years (0.07-5.98); main reasons of discontinuation were toxicity (40.5%) and failure (26.2%). Among 631 patients treated with venetoclax at any line, 100 (15.8%) received BCL2 +/- anti-CD20 as first-line; 170 (26.9%) as second line (125 previously treated with CIT, 27 with BTKi); and, 361 as third or subsequent line. ORR ranged between 71.5% (≥3 lines) with 30.5% CR/CRi to 90.3% (first-line) with 68.1% CR/CRi. Treatment discontinuation was due to toxicity in 28.6% of patients treated in the first-line, and 17.6% and 21.8% of patients treated in second and third-or-higher-line, respectively. Disease progression led to treatment discontinuation in 14.3%, 20.6% and 33.6% in first, second and third-or-higher line, respectively. CIT was used as front-line treatment in 5465 patients (59.6%). Of these, 2070 (37.9%) and 1018 (18.6%) patients received a second and third line of treatment, respectively. The great majority (865/1086 cases, 79.7%) of patients who received a second line before 2014 were retreated with CIT, most commonly Bendamustine-Rituximab (284/1086, 26.1%) and Fludarabine-Cyclophosphamide-Rituximab (252/1086, 23.2%); alemtuzumab monotherapy was used in 55/1086 (5%) of patients. After 2014, 415/984 patients (42.1%) were retreated with BTKi; 93 (9.5%) with venetoclax; 70 (7.2%) with idelalisib; 50 (5%) with Alemtuzumab monotherapy, and 315 (32%) with CIT. Similarly, in the third-or-higher line of treatment, most patients (86.3%) were retreated with CIT before 2014, while BTKi, BCL2i, and PI3Ki were mainly used after 2014 (in 43.1%, 15.7% and 14.7% of cases, respectively). Finally, our cohort included 1075 patients with TP53 aberrations. The ORR of patients receiving BTKis (n=171) as first-line of treatment was 86.5% (22.2 CR+64.3 PR), while the ORR with venetoclax +/- anti-CD20 (n=15) was 91% (45.5% CR+45.5 PR). Patients treated with CIT (n=694) had an ORR of 68.7% (28.3% CR+40.4% PR). In conclusion, in a large international study we provide real world data regarding the selection and sequencing of treatment in CLL, charting a major shift in treatment patterns before and after the introduction of novel trargeted agents and confirming their efficacy even in high-risk CLL. Disclosures Scarfo: Janssen: Honoraria, Other: Travel grants; Astra Zeneca: Honoraria; Abbvie: Honoraria. Iacoboni: BMS/Celgene, Gilead, Novartis, Janssen, Roche: Honoraria. Collado: Abbvie,: Other: pharmaceutical Company, Research Funding; Janssen: Other: Pharmaceutical Company, Research Funding. Galimberti: AbbVie, Janssen: Honoraria, Other: Travel grants; Incyte: Speakers Bureau. García-Serra: AbbVie: Other: Educational grands; Janssen: Other: Educational grants; Novartis: Other: Educational grants. Gozzetti: Janssen: Honoraria; AbbVie: Honoraria. Hatzimichael: Amgen, Roche, Genesis, Novartis, Bristol Mayer Squibb, Celgene, Pfizer: Consultancy; Abbvie, Amgen, Bristol Mayer Squibb, MSD, Gilead, Janssen Cilag, Genesis Pharma, Roche, Takeda: Honoraria. Herishanu: AbbVie: Honoraria, Research Funding; Janssen: Honoraria; Roche: Honoraria; Medison: Honoraria. Jaksic: Roche, Oktal-Pharma/Celtrion, Sandoz: Consultancy, Honoraria. Kater: Janssen, AstraZeneca: Other: Ad Board, steering committee, Research Funding; Abbvie: Honoraria, Other: Ad Board, Research Funding; BMS, Roche/Genentech: Other: Ad Board, , Research Funding; Genmab, LAVA: Other: Ad Board, Steering Committee. Kotsianidis: Astellas: Other: NONE, Research Funding, Speakers Bureau; Genesis: Consultancy, Other: NONE; Janssen Hellas: Consultancy, Other: NONE, Speakers Bureau; Bristol Hellas: Consultancy, Other: NONE, Research Funding, Speakers Bureau; Novartis Hellas: Consultancy, Other: NONE, Research Funding, Speakers Bureau; Abbvie: Consultancy, Other: NONE, Research Funding, Speakers Bureau. Kreitman: NIH: Patents & Royalties: Moxetumomab Pasudotox; Genentech: Research Funding; Teva: Research Funding; AstraZeneca/MedImmune: Research Funding; Innate: Research Funding; GSK/Novartis: Research Funding; Array BioPharma/Pfizer: Research Funding. Laribi: BeiGene: Other: Personal Fees; Jansen: Research Funding; Novartis: Other: Personal Fees, Research Funding; Astellas Phama, Inc.: Other: Personal Fees; AstraZeneca: Other: Personal Fees; Le Mans Hospital: Research Funding; Takeda: Other: Personal Fees, Research Funding; AbbVie: Other: Personal Fees, Research Funding; IQONE: Other: Personal Fees. Lopez-Garcia: Roche: Other: Speaker Honoraria, Travel and accommodation grants; Novonordisk: Other: Speaker Honoraria; Fresenius: Other: Speaker Honoraria; Celgene: Other: Speaker Honoraria; Abbvie: Other: Speaker Honoraria, Advisor, Travel and accommodation grants; Janssen: Other: Speaker Honoraria, Advisor, Travel and accommodation grants, Research Funding. Milosevic: Roche: Honoraria; Abbvie,: Honoraria; Janssen: Honoraria; Sandoz: Honoraria. Reda: Beigene: Consultancy; Astra Zeneca: Consultancy; Abbvie: Consultancy; Janssen: Consultancy. Ruchlemer: AbbVie: Consultancy, Honoraria, Research Funding. Šimkovič: Janssen, Gilead, Roche, AstraZeneca, and AbbVie: Other: consultancy fees, advisory board participation fees, travel grants, and honoraria; University Hospital Hradec Kralove: Current Employment; AbbVie: Consultancy, Current equity holder in publicly-traded company, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses; AstraZeneca: Consultancy, Membership on an entity's Board of Directors or advisory committees; Janssen-Cilag: Consultancy, Honoraria, Other: Travel, Accommodations, Expenses; Merck: Current equity holder in publicly-traded company; Eli Lilly: Current equity holder in publicly-traded company; J&J: Current equity holder in publicly-traded company; Gilead: Other: Travel, Accommodations, Expenses. Špaček: AbbVie, AstraZeneca, Gilead, Janssen, and Roche: Honoraria. Tadmor: Janssen: Consultancy, Honoraria, Research Funding; AbbVie: Consultancy, Honoraria, Research Funding. Visentin: Italfarmaco and Gilead: Speakers Bureau. Vassilakopoulos: AstraZeneca: Honoraria; Amgen: Honoraria, Research Funding; Pfizer: Research Funding; Dr. Reddy's: Research Funding; Novartis: Consultancy, Honoraria; GlaxoSmithKline: Honoraria, Other: Travel; Merck: Honoraria, Research Funding; Integris: Honoraria; Roche: Consultancy, Honoraria, Other: Travel; Genesis Pharma: Consultancy, Honoraria, Other: Travel; Takeda: Consultancy, Honoraria, Other: Travel, Research Funding; AbbVie: Consultancy, Honoraria; Karyopharm: Research Funding. Vitale: Janssen: Honoraria. Yáñez: Gilead-Kite, Janssen, AbbVie, AstraZeneca, Beigene, Roche, Pfizer, Jazz, BMS, and Merck: Other: Advisory board participation fees ; Janssen, AbbVie, AstraZeneca, Gilead-Kite, Roche, Pfizer, and Merck: Speakers Bureau. Antic: AbbVie, Janssen, and Roche: Honoraria. Coscia: Janssen: Honoraria, Other, Research Funding; Gilead: Honoraria; AstraZeneca: Honoraria; AbbVie: Honoraria, Other. Cuneo: AstraZeneca: Consultancy, Speakers Bureau; Janssen: Consultancy, Speakers Bureau; Gilead: Consultancy, Speakers Bureau; AbbVie: Consultancy, Speakers Bureau. Gaidano: Beigene: Membership on an entity's Board of Directors or advisory committees; Incyte: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Astrazeneca: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Abbvie: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Guièze: Janssen: Consultancy, Honoraria; Abbvie: Consultancy, Honoraria, Research Funding; Roche: Consultancy, Honoraria; Astrazeneca: Consultancy, Honoraria. Laurenti: AstraZeneca: Consultancy, Honoraria; AbbVie: Consultancy, Honoraria, Research Funding; Roche: Honoraria, Research Funding; Gilead: Honoraria; Janssen: Consultancy, Honoraria; BeiGene: Honoraria. Murru: Abbvie: Consultancy, Honoraria, Other: travel and accommodation; Janssen: Consultancy, Honoraria. Sportoletti: AstraZeneca: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; AbbVie: Consultancy, Honoraria. Tam: Beigene: Research Funding; Janssen: Research Funding; Abbvie: Research Funding; Loxo: Honoraria; Beigene: Honoraria; Janssen: Honoraria; Abbvie: Honoraria. Trněný: Amgen: Consultancy, Honoraria; Bristol-Myers Squibb: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses; Gilead Sciences: Consultancy, Honoraria, Other: Travel, Accommodations, Expenses; Incyte: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses; MorphoSys: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Roche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses; Takeda: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses; Celgene: Consultancy; 1st Faculty of Medicine, Charles University, General Hospital in Prague: Current Employment; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Portola: Honoraria, Membership on an entity's Board of Directors or advisory committees; AstraZeneca: Honoraria; AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, Accommodations, Expenses. Bosch Albareda: Janssen: Consultancy, Honoraria, Research Funding, Speakers Bureau; Gilead: Consultancy, Honoraria; Abbvie: Consultancy; AstraZeneca: Consultancy, Honoraria, Research Funding; Roche: Consultancy, Honoraria, Research Funding, Speakers Bureau; Takeda: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; Kite: Honoraria; Sanofi: Honoraria; Lilly: Honoraria. Doubek: Janssen-Cilag, AbbVie, AstraZeneca, Amgen, Gilead, Novartis: Honoraria, Research Funding. Chatzidimitriou: Abbvie: Honoraria, Research Funding; Janssen: Honoraria, Research Funding. Ghia: AbbVie: Consultancy, Honoraria, Research Funding; Acerta/AstraZeneca: Consultancy, Honoraria, Research Funding; AstraZeneca: Consultancy, Honoraria, Research Funding; ArQule/MSD: Consultancy, Honoraria; BeiGene: Consultancy, Honoraria; Celgene/Juno/BMS: Consultancy, Honoraria; Gilead: Consultancy, Research Funding; Janssen: Consultancy, Honoraria, Research Funding; Roche: Consultancy, Honoraria; Sunesis: Research Funding. Stamatopoulos: AstraZeneca: Honoraria, Research Funding; Abbvie: Honoraria, Research Funding; Gilead: Honoraria, Research Funding; Janssen: Honoraria, Research Funding.

  • Open Access
    Authors: 
    Hong Zhu; Wael Alhajyaseen; Miho Iryo-Asano; Hideki Nakamura; Charitha Dias;
    Publisher: Elsevier BV
    Country: Qatar

    The emergence of Autonomous Vehicles (AVs) could provoke unexpected challenges in urban traffic environments. One such crucial challenge is the conflicts between pedestrians and AVs, particularly on unsignalized mid-block crosswalks (UMC), where pedestrians are exposed to the AV flow. This study investigates the efficiency and safety performance of a UMC in the presence of both AVs and pedestrians considering the diversities in their behaviors. Through empirical analyses, two pedestrians’ crossing decision models are built and four groups of speed profiles are classified. Meanwhile, based on previous literature, defensive and competitive driving strategies are assumed for AVs. The simulation is implemented on an agent-based framework that can dynamically reproduce the kinematic interactions between pedestrians and vehicles. Results indicated that with a reasonable safety margin (2.5 s), percentages of low post encroachment time events for competitive AVs with different pedestrian types are smaller than defensive AVs with differences of 0.2% to 2.9%. The average delays of competitive AVs for all pedestrian types are smaller than defensive AVs with a maximum estimated difference of 39 s. Moreover, the analysis showed that lowering the speed limit may reduce the crash rate of competitive AV up to 0%. It is also found that the pedestrians who make reckless crossing decisions and change their speed drastically during the crossing process are more likely to incur crashes with competitive AVs. Therefore, if pedestrian behaviors can be regulated reasonably, competitive AVs with appropriate parameter settings are most suitable for UMC in the future. This publication was made possible by the Qatar–Japan Research Collaboration Application Award [M-QJRC-2020-8] from Qatar University. The statements made herein are solely the responsibility of the authors. This research is supported by The Kurata Grants No. 1397 of Hitachi Global Foundation .

Send a message
How can we help?
We usually respond in a few hours.