Good Condition Research Articles

CHARACTERISTICS OF NEWBORNS FROM WOMEN WHO CONTRACTED COVID-19 DURING PREGNANCY

Objective: to study characteristics of newborns from women who contracted COVID-19 during pregnancy. Material and methods. The condition of newborns was analyzed based on 210 primary medical records of women who contracted COVID-19 during pregnancy (main group). These findings were compared with similar data obtained from a control group of 210 women who did not have COVID-19 during pregnancy, selected using the case-control method. To assess the newborns' condition, gestational age at birth, anthropometric measurements, and Apgar scores were examined. Research results. It was found that women who contracted COVID-19 during pregnancy are at an increased risk for perinatal complications. Significant differences were observed in gestational age, birth weight, and Apgar scores between the main and control groups. Babies born to mothers in the main group were more frequently premature compared to the control group (P<0.05), where all newborns were full-term. In the main group, 68.6% of newborns were in satisfactory condition, with an Apgar score of 8. In 13.8% of cases, the score was 7, while 12.4% had a score of 6, and 5.2% had a score of 5. In contrast, 93.8% of newborns in the control group had an Apgar score of 8, 5.7% scored 7, and 0.5% scored 6 (p<0.05). Furthermore, in the main group, 84.3% of newborns were discharged home in satisfactory condition, while 14.7% required transfer to the intensive care unit, and 1.0% died. In the control group, 99.0% of newborns were discharged home in satisfactory condition, and 1.0% were transferred to intensive care (p<0.05). Conclusions. The study revealed that women who contracted COVID-19 during pregnancy are at an increased risk of perinatal complications. Significant differences in gestational age, birth weight, and Apgar scores were observed between the main and control groups (P<0.05). Newborns in the main group were more frequently premature compared to those in the control group, where all births were full-term (P<0.05). It is recommended that women who had COVID-19 during pregnancy be classified as a "risk group" for perinatal complications.

Characterization of Thrombocytopenia in Pediatric Patients in Noncritical Hospital Setting: An Institutional Review From Pakistan

Pediatric thrombocytopenia is frequently observed in critical care and oncology settings with an increased risk of bleeding and platelet transfusions. However, little is known about low platelets in childhood during seasonal influence. This study aimed to evaluate the frequency and severity of pediatric thrombocytopenia in the postflood period. The patients aged 1 to 18 years with thrombocytopenia (platelet count <150×109/L) were studied from August to December 2022 after institutional ethical approval (ERC-Path-2022-8044-23395). Data was collected from electronic health records and laboratory information systems. Of 2318 admitted patients, 192 (8.3%) including 128 males and 64 females had thrombocytopenia. The median (IQR) age was 12 (8 to 15) years. Mild, moderate, and severe thrombocytopenia were seen in 109 (56.8%), 76 (39.5%), and 7 (3.6%) patients, respectively. Concomitant leucopenia was observed in 77 of 192 patients (40.1%). Infection was the predominant cause of low platelets (N=175 or 91.1%). Only 15 patients (7.8%) had grade 1/2 bleeding. Overall, 176 patients (92%) were discharged in stable conditions and no mortality was observed. The frequency of pediatric thrombocytopenia in the noncritical and nononcological care settings was <10% and mostly observed in association with underlying infections. The frequency of bleeding manifestation and platelet transfusions was minimal in this group.

The potential for predicting neonatal disabilities in preterm infants

The urgent task of modern pediatricians and neonatologists is to predict the course of the early neonatal period, during which the basic adaptive mechanisms of newborn children are in an unstable state. This is particularly important for the study of premature newborns, who are at high risk for an unfavorable outcome.Purpose. The aim of this study was to investigate the nature of early neonatal adaptation in children born between 32- and 36-weeks’ gestation, from mothers with burdened obstetric and gynecological histories and concomitant medical conditions.Material and methods. Out of 75 patients, we divided children born against a background of placental abruption and pre-eclampsia into separate groups. We provide a comparative analysis of their obstetric, gynecological, and medical histories, as well as their pre-dictive factors, somatic status dynamics, and laboratory and instrumental examinationsResults. Analysis of the data showed that in late preterm newborns, the presence of placental abruption in the history of 100% of cases led to the development of general somatic distress, with deterioration in hemodynamic and respiratory parameters, requiring transfer to the second phase of care. In children born preterm due to severe preeclampsia or other causes, stable severe conditions were observed in 33.3 and 39.6%, respectively, and 53.9 to 60% of infants required respiratory support.Conclusion. These findings allow for individualized assessment of a newborn’s condition in the first few days of life, based on predictive factors that may lead to a breakdown in compensatory responses.

Hydrological changes and its impacts on prehistoric human welfare in the western Tibetan Plateau since the last deglaciation

In recent decades, the rapidly changing climate environment in the Tibetan Plateau (TP) poses significant challenges to human survival and future sustainable development. The suitability and stability of the climate in the TP undoubtedly affected the living conditions and welfare of prehistoric humans. However, few studies have attempted to link climate stability and the survival of ancient humans, especially considering their lesser adaptability in responding to rapid environmental changes. The Xiada Co is a Neolithic period archaeological site in the western TP. In this study, we reconstructed the hydrological changes in the basin over the past 15,000 years using X-ray fluorescence (XRF) elemental analysis on the Xiada Co cores. The XRF results revealed three main paleoenvironmental units during the entire study interval. The late Pleistocene prior to ~10,000 cal year BP was characterized by more rapidly fluctuating hydrologic conditions. The early and middle Holocene (~10,000–4000 cal year BP) by stable hydrologic conditions, and the late Holocene to present by a return to more variable conditions. Using the calculation method of Square Chord Distance (SCD), a quantitative dissimilarity comparison was made regarding the climate variations in the western TP for 15 time periods. The results showed that the climate and hydrology were relatively stable during the period of occupation of the region (8500–7500 years BP), which provided a stable and suitable living environment for the hunter-gatherers at the site. This study illustrates how the paleoenvironment influenced the survival of hunter-gatherers in the extremely harsh western TP.

Autophagy in Acute Lung Injury.

Acute lung injury (ALI) is a critical condition marked by rapid-onset respiratory failure due to extensive inflammation and increased pulmonary vascular permeability, often progressing to acute respiratory distress syndrome (ARDS) with high mortality. Autophagy, a cellular degradation process essential for removing damaged organelles and proteins, plays a crucial role in regulating lung injury and repair. This review examines the protective role of autophagy in maintaining cellular function and reducing inflammation and oxidative stress in ALI. It underscores the necessity of precise regulation to fully harness the therapeutic potential of autophagy in this context. We summarize the mechanisms by which autophagy influences lung injury and repair, discuss the interplay between autophagy and apoptosis, and examine potential therapeutic strategies, including autophagy inducers, targeted autophagy signaling pathways, antioxidants, anti-inflammatory drugs, gene editing, and stem cell therapy. Understanding the role of autophagy in ALI could lead to novel interventions for improving patient outcomes and reducing mortality rates associated with this severe condition.

Mechanical Analysis of the Critical Conditions for Trapping and Detachment of Microscale Air Bubbles on the Pure Water Freezing Front.

Icing is a widespread phase change phenomenon with implications for daily life and industrial production. Air bubbles form on the freezing front of pure water with dissolved air during the icing, which may affect the physical properties of ice. Controlling the behavior of air bubbles will be one method to change the physical properties of ice. To analyze the critical conditions for trapping and detachment of microscale air bubbles on a pure water freezing front, a mathematical model describing the forces on air bubble is developed on the basis of the principle of force equilibrium. Results show that the average accuracy of the present model in predicting the average air bubble detachment radius is about 62%, which is 30% higher than the model with the best prediction accuracy in the literature. Buoyant, temperature gradients, and hydrodynamic forces push air bubbles to detach from the freezing fronts, while adhesion force and gravity impede their detachment. Temperature gradient and adhesion forces are the main factors affecting the detachment of air bubbles from freezing fronts. The temperature gradient has the greatest effect on the air bubble detachment radius, while the tilt angle and liquid density have a lesser effect. When the temperature gradient is increased from 1000 to 10 000 K/m, the air bubble detachment radius decreases by 37.78%. Studying the forces acting on the air bubbles on the pure water freezing front is an important reference for the production of special ice bodies, phase change cold storage, and de-icing technology.

Detection of a Gossypiboma as a Retrocardiac Mass in a Female Patient with a History of Coronary Artery Bypass Graft

Introduction: "Gossypiboma," also known as "textiloma," refers to retained surgical items left in the body after an operation. These retained items can lead to a range of issues, from asymptomatic cases to life-threatening complications. Diagnostically challenging, gossypibomas can mimic malignant masses, making it essential to consider them in the differential diagnosis of postoperative patients with unexplained symptoms. Imaging is crucial for detection and management. Case Presentation: A 69-year-old female with a history of coronary artery bypass graft (CABG) surgery presented with exertional shortness of breath. Imaging revealed a large mass near the left atrium. Initially suspected to be a tumor, further investigation identified it as retained surgical gauze from her surgery ten years prior. Despite the mass, the patient exhibited only mild symptoms, and given her stable condition, regular follow-ups were recommended. Conclusions: Gossypibomas are rare but serious complications that may surface years after surgery. This case highlights the importance of meticulous surgical practices and careful postoperative monitoring. It underscores the need for accurate gauze counting and effective communication in the operating room to prevent errors that can lead to health risks and potential legal issues.

Simultaneous Modulation on Solvation Shell and Electrode Interface for Reversible Zinc Anode Realized by a Mutiplefunctional Additive

AbstractThe inferior reversibility of Zn metal anode caused by undesired Zn dendrite and severe interfacial side reactions has to be addressed for the commercial application of Zinc ion batteries (ZIBs). Here, a multiple functional sodium benzaldehyde 2,4‐disulfonate(B24DADS) additives with various blocks of polar sulfonate group, Lewis basic aldehyde groups, and hydrophobic benzene ring is proposed to regulate the solvation structure of Zn2+, construct an H2O‐poor and zincophilic dual electric layer structure, and create a passive SEI on the Zn anode surface, thus restaining dendrite growth and interfacial side reactions. Furthermore, uniform deposition mechanics of the Zn are revealed by the synergistic effect of induced deposition, additive‐derived SEI formation, and texture regulation. In addition, Na+ can also limit the growth of zinc dendrites based on electrostatic shielding mechanisms. Therefore, the multifunctional B24DADS additive grants the anode to deliver remarkable electrochemical performance. Under critical test conditions (20 mA cm−2/20 mAh cm−2), the zinc provides superior long cycling (3700 h) with a low polarization voltage (0.02 V). B24DADS containing electrolyte is well matched with manganese dioxide cathode. This effort renders a promising way to explore advanced additives with unique molecular structures for addressing zinc dendrite growth and rampant side effects.

Successful experience of hip arthroplasty with a unipolar endoprosthesis

Introduction. Fractures of the femoral neck occupy a significant place in traumatology and orthopedics and represent a serious pathological problem. Without surgical treatment, this pathology leads to complications and death of the patient within a year. Hip replacement is the choice of treatment method that allows the injured patient to be mobilized as early as possible. This promotes and has a positive effect on the timing and effectiveness of rehabilitation measures and minimizes the risk of developing possible complications. The purpose of this publication is to demonstrate the successful experience of treating a patient with a fracture of the right femoral neck with displacement of fragments using endoprosthetics. Materials and methods. To write the article, we used medical documentation data from a trauma hospital, the results of instrumental research and dynamic observation of the patient. A search was also carried out in the open electronic scientific databases PubMed of the US National Electronic Medical Library and the databases of the Russian scientific electronic library elibrary, using keywords and phrases: Results. Endoprosthesis replacement of the hip joint with a unipolar endoprosthesis was performed. On the sixth day after the surgical intervention, the patient was discharged in satisfactory condition for outpatient treatment by a traumatologist at his place of residence. The wound and sutures have no signs of inflammation, sensitivity and blood supply to the limb are preserved. The patient moves independently using a walker. Discussion. Analyzing the results of surgical treatment in the described clinical case, we can conclude that the method of hip replacement is highly effective in elderly people. Conclusion. Endoprosthesis replacement surgery is low-traumatic and allows the patient to be mobilized early. Our experience allows us to believe that treatment with endoprosthetics is effective for fractures of the femoral neck and allows us to achieve positive results in the early stages.

Comparative analysis of addiction severity index in methadone maintenance treatment: impact of concurrent methamphetamine use among patients in Rasht, Iran 2022–2023

ABSTRACT Introduction Methadone Maintenance Treatment (MMT) is widely used to manage opioid addiction, especially in Iran. Recent research highlights an increasing trend in methamphetamine use among individuals who are opioid-dependent and undergoing MMT. This study aimed to evaluate the differences in addiction severity between patients using both methadone and methamphetamine and those on methadone alone. Method This cross-sectional study took place at four MMT centers in Rasht, Guilan Province, Iran, from 2022–2023. Using convenience sampling, we selected participants aged 18 to 64 who had been receiving treatment at MMT centers for at least six months. Demographic data and Addiction Severity Index (ASI) scores were collected for two groups: those using methadone alone and those also using methamphetamine. Data analysis was conducted with SPSS version 26, using a significance threshold of 0.05. Results Of the 140 participants, 120 were male and 20 female. The Mann–Whitney test found no significant differences in medical status between the groups across six domains. However, five other domains showed significantly lower ASI scores for the methadone-only group compared to the methamphetamine users. Conclusion Concurrent methamphetamine use with MMT may negatively impact functional and health outcomes, highlighting the need for non-pharmacological psycho-social treatments to help curb methamphetamine use in this population.

The Unusual Presentation of Non-ST Elevation Myocardial Infarction Following Acute Carbon Monoxide Poisoning in an Elderly Female: A Case Report

Carbon monoxide (CO) poisoning is a leading cause of poisoning-related deaths, particularly affecting organs with high oxygen demands such as the heart and brain. Cardiac complications, including non-ST elevation myocardial infarction (NSTEMI), can occur due to CO poisoning but are not frequently reported in the elderly. We present the case of an 82-year-old female with a medical history of diabetes, hypertension, dyslipidemia, and previous ischemic heart disease. She was brought to the emergency department after being found drowsy in a closed room with a burning charcoal heater. The initial assessment revealed a carboxyhemoglobin level of 33.5%, which decreased to 9.3% after high-flow oxygen therapy and hyperbaric oxygen therapy (HBOT). Laboratory tests indicated elevated troponin levels, and an ECG showed asymmetrical T-wave inversion and ST depression. Despite the improvement in carboxyhemoglobin, the patient experienced persistent chest pain and rising troponin levels. She was treated with dual antiplatelet therapy and low molecular weight heparin as per acute coronary syndrome protocol, leading to a gradual improvement and a subsequent discharge in a stable condition. This case highlights the potential for CO poisoning to induce NSTEMI in elderly patients. A prompt diagnosis and appropriate management, including the use of HBOT, were crucial for the patient’s recovery.

Clinical outcomes and associated bacterial and fungal microbiota changes after high dose probiotic therapy for severe alcohol-associated hepatitis: An observational study.

Alcohol-associated hepatitis (AH) is a critical condition with high mortality rates and is worsened by infections. Organ failure is strongly associated with intestinal dysbiosis. Emerging research suggests that gut microbiota modulation with probiotics can improve AH outcomes. This study investigated the clinical and microbiome effects of high-dose probiotic infusion (HDPI) compared with corticosteroid therapy (CST) and fecal microbiota transplantation (FMT) in severe AH. Patients with biopsy-proven severe-AH were enrolled from March 2019 to June 2020 and matched for age and disease severity. The patients received HDPI (n = 20), FMT (n = 16), or CST (n = 14). HDPI consists of a potent probiotic mix delivered via a nasoduodenal tube for 6 days. The primary outcome was survival at 90-days. Stool samples were subjected to 16S and 18S rRNA sequencing to assess significant bacterial and fungal taxa and their interactions at baseline and post treatment. At 90-days, survival rates were 55%, 64.3%, and 87.5% (HDPI, CST, respectively). HDPI did not beneficially impact bacterial alpha-diversity but significantly altered beta-diversity. Notably, the number of pathogenic bacteria, such as Bilophila and Roseburia increased. Fungal analysis revealed no significant changes in alpha diversity, but significant dissimilarities in beta diversity post-HDPI. New fungal genera such as Basidiomycota and Phragmoplastophyta have emerged, with significant deleterious expansion in fungal communities and damaging modifications between fungal-bacterial interactions. HDPI failed to outperform CST in improving the clinical outcomes of patients with severe AH. While HDPI influenced both bacterial and fungal microbiomes, it also led to the persistence of pathogenic communities. FMT showed superior survival outcomes, highlighting the urgent need for further controlled trials.

Local Flaps for Concomitant Reconstruction of 3 Adjacent Forehead Defects: Is It Feasible?

The cornerstones of forehead reconstruction are the provision of adequate skin paired with a satisfactory cosmetic outcome without hairline and eyebrows distortion. Several techniques have been described over the years to reconstruct sizable defects. Currently, an individualized approach, based on the patient's medical status and needs, the defect characteristics, and the local tissue quality and availability, should be considered for an optimal outcome. This case exemplifies the reliability of local flaps' combination to reconstruct concurrently 3 adjacent forehead defects, should innovative thinking and adequate planning be applied.

Effective blind bilateral superficial cervical plexus block for tracheostomy tube insertion in a geriatric patient with Ludwig angina with hypertension in resource constrained area: a case report

IntroductionLudwig angina is a rare, rapidly spreading submaxillary, submandibular, and sublingual necrotizing life-threatening widespread cellulitis of the soft tissue on the floor of the mouth that can cause fatal complications because of airway obstruction. Currently, there are few published studies assessing the efficacy of superficial cervical plexus block for airway surgery and there is no agreement in the literature about airway management. The published recommendations differ and are based on the authors’ own experiences and available resources. This report aimed to provide insight into critical patient management by performing regional anesthesia with fewer complications to the cardiovascular and respiratory systems.Case presentationWe report the case of a 70 year-old hypertensive Black Ethiopian woman with American Society of Anesthesiologist–Physical Status class III and hypertension, who was admitted to the hospital for treatment by her surgeon. The surgeon diagnosed her with Ludwig angina. After adequate physical examination and laboratory investigation, she arrived at the operation room for exploration and drainage of the abscess with a superficial cervical plexus block. She arrived safely at the adult intensive care unit for frequent suctioning. The block was effective until 6 h after the procedure with visual analogue scale (2/10), her vital signs remained stable throughout the postoperative period, and then the tracheostomy tube was removed by the surgeon after 10 days. The patient’s hemodynamic status and breathing effort were satisfactory, and she was discharged 15 days later.Clinical discussionProper airway management is critical for the survival of patients diagnosed with Ludwig angina. According to recent studies, an increasing number of patients with Ludwig angina require intensive care unit admission for tracheal intubation and mechanical breathing. However, it is uncertain whether intensive care reduces the death rate in patients with Ludwig angina. Finally, it is suggested that studies with large sample sizes and strong levels of evidence be conducted to conclude the effectiveness of superficial cervical plexus block for airway emergency surgeries.ConclusionManagement of the airway in patients with Ludwig angina is challenging. Clinicians must take precautions and make sharp decisions on the basis of a variety of circumstances, including the availability of equipment at medical facilities, such as fiberoptic intubation equipment; the anesthetist’s level of experience, such as performing superficial regional block and good mask ventilation; and the patient’s medical status at the time of presentation. As a result, intervention needs to be quick so as to avoid airway obstruction and further complications.

A cross-sectional study of anesthesia medical staff's occupational and health status in nongovernment medical institutions in China.

Nongovernment medical institutions have gradually become a significant part of China's healthcare system, with a growing numbers of staff. However, the current status of anesthesiology staff in these institutions is unclear. To gain insight into this situation and to compare it with public hospitals, the national anesthesia professional committee of the Chinese Nongovernment Medical Institutions Association (CNMIA) designed and conducted the national cross-sectional survey. We conducted a national cross-sectional study to investigate the occupational and health status of anesthesiology staff in Nongovernment medical institutions. Additional questions were included for the directors of the anesthesiology department to understand their work stress and the reasons for employee turnover. The electronic questionnaire was created using Questionnaire Star and distributed by Anesthesia Professional Committee of the CNMIA through the QR code links and WeChat. A total of 1111 questionnaires were collected, including 989 from anesthesiologists and 122 from nurse anesthetists. The overall job satisfaction score (MSQ) was 75.57 ± 12.32 and the average fatigue score (MFI-20) was 49.10 ± 10.90. High-risk factors for severe fatigue included being aged 31-40, holding a middle title, frequently working night shifts, having long working hours, and participating surgeries classified as ASA III or higher. The most common disease reported was difficulty falling asleep/insomnia. Multivariate logistic regression analysis showed that men (OR = 0.662, 95% CI: 0.482-0.909, p < 0.05), those with a bachelor's degree (OR = 2.152, 95% CI: 1.186-3.903, p < 0.05), individuals with heavy workloads (OR = 2.999, 95% CI: 1.493-6.024, p < 0.01), poor health (OR = 4.280, 95% CI: 1.216-15.057, p < 0.05), and high MFI-20 scores (OR = 1.085, 95% CI: 1.067-1.103, p < 0.001) were more likely to suffer from insomnia. Directors identified medical quality and safety management as their main source of stress and low income as the primary reason for employee resignation. Nongovernment medical institutions have fewer employees, similar workloads, relatively low job stress and higher job satisfaction compared to public hospitals. Low income and difficulty falling asleep/insomnia are significant issues that require attention.

Persistent Hypoglycemia in Premature, Small for Term, and Low Birth Weight Neonates from Mothers with a History of Severe Preeclampsia

Background: Neonatal hypoglycemia is a metabolic problem that is often found in the NICU and is one of the causes of permanent brain damage in infants. The diagnosis of persistent hypoglycemia and its causes are still controversial. Case: A male baby was born to a mother with severe preeclampsia at 36 weeks of gestation, with a birth weight of 1600 grams. At 1 hour of age, he experienced hypoglycemia that lasted more than 72 hours with the lowest blood sugar of 18 mg/dL, and experienced hyperkalemia (potassium level 6.1 mmol/L). The baby is diagnosed as persistent hypoglycemia. The clinical condition improved after being given dextrose and dexamethasone, and was discharged in stable condition. Conclusion: Management of persistent hypoglycemia depends on the cause. Diagnosis refers to risk factors before or after birth.

Real-time autonomous control of a continuous macroscopic process as demonstrated by plastic forming.

To meet the need for more adaptable and expedient approaches in research and manufacturing, we present a continuous autonomous system that leverages real-time, in situ characterization and an active-learning-based decision-making processor. This system was applied to a plastic film forming process to demonstrate its capability in autonomously determining process conditions for specified film dimensions without human intervention. Application of the system to nine film dimensions (width and thickness) highlighted its ability to explore the search space and identify appropriate and stable process conditions, with an average of 11 characterization-adjustment iterations and a processing time of 19 minutes per width, thickness combination. The system successfully avoided common pitfalls, such as repetitive over-correction, and demonstrated high accuracy, with R2 values of 0.87 and 0.90 for film width and thickness, respectively. Moreover, the active learning algorithm enabled the system to begin exploration with zero training data, effectively addressing the complex and interdependent relationships between control factors (material supply rate, applied force, material viscosity) in the continuous plastic forming process. Given that the core concept of this autonomous process can, in principle, be transferred to other continuous material processing systems, these results have implications for accelerating progress in both research and industry.

Exploring the effects of institutional logics on entrepreneurial opportunity evaluations in emerging economies

ABSTRACT It is becoming increasingly crucial to understand how institutional logics influence entrepreneurial behaviors and decisions as they impact job creation and startups globally. This research hypothesizes how two different logics—family and market—will influence entrepreneurial decision-making and action. To test our hypotheses, we conducted a two-wave study using an experimental approach to gather data from 326 aspiring entrepreneurs in India who made 630 opportunity evaluation decisions. We analyzed this dataset using subgroup regression analyses. We find significant effects of institutional logics on entrepreneurial decision-making. Particularly, we find that in contrast to extant theory from developed contexts, in emerging economies such as India, the family logic has a stronger influence on willingness to invest in entrepreneurial opportunities as compared to the market logic. We also identify critical boundary conditions of the decision context that make the effect of institutional logic more or less salient. Our findings highlight that financial stakes and support from close associates strengthen the relationship between the family logic and willingness to invest. However, reputational stakes were found to significantly weaken the relationship between the family logic and willingness to invest. Thus, our research contributes to the literature on entrepreneurship by exploring microprocesses of institutional logics and the impact of the family logic on entrepreneurial decisions in emerging markets. Moreover, we extend the institutional logics literature by highlighting that the logics act not only as a “lens” but also as a “mirror,” helping entrepreneurs predict how certain stakeholders will interpret and react to their decisions and actions.

The effects of communication topology on mixed traffic flow: modelling and analysis

This paper aims to evaluate the combined impact of the communication topology (CT) and vehicular spatial distribution (SD) on mixed traffic of human-driven vehicles (HDVs) and connected and autonomous vehicles (CAVs). A generalized car-following (CF) model is presented to capture mixed traffic dynamics, integrating the effects of the CT, human reaction time, information delay and the optimal velocity changes with memory. Then, the linear stable condition of the model is derived using the perturbation method. Finally, extensive simulations are conducted under different CTs (i.e., multiple-predecessor leader following (MPLF) topology, predecessor following (PF) topology, and predecessor-leader following (PLF) topology) and six kinds of SDs. The results reveal that the MPLF topology demonstrates the best steady performance (i.e., stability) and dynamic performance (i.e., smoothness), and that the SD where CAVs are concentrated at the front of the traffic flow shows superior dynamic performance.

Stability of steady-state solutions of Jeffcott rotor with varying rotational speed

AbstractThe behavior of flexible rotating systems with varying rotational speeds is essential in engineering applications. Analysis methods that consider linear dynamic models and many existing nonlinear analysis approaches assume constant rotational speed. These approaches are unsuited to study the dynamic interaction between driving torque and whirling motion in this class of applications. In this paper, an analysis of the stability and control of a Jeffcott rotor under varying operational conditions is presented. A nonlinear dynamic model of the system is formulated to enable a detailed stability and parametric analysis. A proportional-integral (PI) torque command is employed to achieve a steady-state rotational speed. Assuming constant lateral control effort, system equilibrium points and their stability characteristics as functions of the system’s parameters are analyzed. A control law that minimizes the lateral effort is derived. A feedback proportional lateral control strategy is introduced to enhance the system’s region of stability, particularly in the supercritical speed range. Finally, a simulation study is conducted to validate the analytical findings. Simulation results demonstrate the effectiveness of the proposed approach for defining stable operating conditions and improving system performance.