Trajectory Optimization of a Subsonic Unpowered Gliding Vehicle Using Control Vector Parameterization

In many aero gliding vehicles, achieving the maximum gliding range is a challenging task. A frequent example is the breakdown of an engine during flight or the use of unpowered stand-off weapons. When an unpowered stand-off weapon begins gliding at a given height, it eventually strikes the ground after some distance, and height is considered a stopping constraint in this general condition. To avoid the time-scaling approach for the free time optimal problem, the maximum stoppable time with a stopping constraint is addressed to attain the maximum glide range. This problem can be chosen as an optimal gliding range problem which can be solved by direct or indirect methods. In this paper, the inverted Y-tail joint stand-off weapon is selected as the subsonic unpowered gliding vehicle (SUGV). After being released from dispersion points, the SUGV has to face fluctuating gliding flight because of flight phase transition that causes gliding range reduction. To achieve a damped and steady gliding flight while maximizing the gliding range, we propose a non-uniform control vector parameterization (CVP) approach that uses the notion of exponential spacing for the time vector. When compared with the maximum step input and conventional uniform CVP approach, simulations of the proposed non-uniform CVP approach demonstrate that the SUGV exhibits superior damping and steady gliding flight, with a maximum gliding range of 121.278 km and a maximum horizontal range of 120.856 km

Trajectory Optimization of a Subsonic Unpowered Gliding Vehicle Using Control Vector Parameterization

In many aero gliding vehicles, achieving the maximum gliding range is a challenging task. A frequent example is the breakdown of an engine during flight or the use of unpowered stand-off weapons. When an unpowered stand-off weapon begins gliding at a given height, it eventually strikes the ground after some distance, and height is considered a stopping constraint in this general condition. To avoid the time-scaling approach for the free time optimal problem, the maximum stoppable time with a stopping constraint is addressed to attain the maximum glide range. This problem can be chosen as an optimal gliding range problem which can be solved by direct or indirect methods. In this paper, the inverted Y-tail joint stand-off weapon is selected as the subsonic unpowered gliding vehicle (SUGV). After being released from dispersion points, the SUGV has to face fluctuating gliding flight because of flight phase transition that causes gliding range reduction. To achieve a damped and steady gliding flight while maximizing the gliding range, we propose a non-uniform control vector parameterization (CVP) approach that uses the notion of exponential spacing for the time vector. When compared with the maximum step input and conventional uniform CVP approach, simulations of the proposed non-uniform CVP approach demonstrate that the SUGV exhibits superior damping and steady gliding flight, with a maximum gliding range of 121.278 km and a maximum horizontal range of 120.856 km

A Cross-Sectoral Investigation of the Energy–Environment–Economy Causal Nexus in Pakistan: Policy Suggestions for Improved Energy Management

This paper explored the energy–environment–economy (EEE) causal nexus of Pakistan, thereby reporting the causal determinants of the EEE nexus by employing the newly developed modified Peter and Clark (PC) algorithm. The modified PC algorithm was employed to investigate the causal ordering of energy consumption, CO2 emissions and economic growth across Pakistan’s domestic, industrial, transportation and agricultural sectors. An empirical comparison, i.e., following Monte Carlo simulation experiments demonstrates that the proposed modified PC algorithm is superior to the original PC proposition and can differentiate between true and spurious nexus causalities. Our results show that significant causality is running from energy consumption in industrial and agricultural sectors towards economic growth. There is no causal association between energy consumption and economic growth in the domestic and transportation sectors. On the other hand, causality runs from energy consumption in the transportation, domestic and industrial sectors towards CO2 emissions. It is concluded that energy consumption in industrial and agricultural sectors leads to economic growth alongside the associated CO2 emissions. On the other hand, the contribution of domestic and transportation sectors in economic growth is trivial with significant CO2 emissions. This paper provides novel empirical evidence of impacts of energy mismanagement at sectoral levels, economic output and environmental consequences; alongside policy recommendations for sustainable energy-based development on the national scale

Real-time implementation of nonlinear model predictive control for high angle of attack Maneuvers in fighter aircrafts using deep learning

ABSTRACTNonlinear model predictive control (NMPC) provides a nice framework for accounting for multivariable nonlinear dynamics subject to constraints; however, the cost of implementing NMPC is high due to the need to solve a large-scale nonlinear program to optimality in real-time. This research is focussed on the design of real-time solution to NMPC (low computations) for fast dynamic systems. In this work, a comprehensive and innovative solution based on a deep learning-based approximate NMPC scheme has been proposed to overcome these computational challenges. The main idea is to learn a deep neural network followed by the symbolic simplification of the NMPC law, whose evaluation cost and memory footprint can be optimized offline. Since not all the states of the system are measured, we also combine the deep learning based NMPC approach with an unscented Kalman filter (UKF) as well as show how this scheme can be easily modified to be offset-free (i.e. remove steady-state error due to persistent disturbances and modelling error). The proposed approach is implemented on a highly fast dynamic system (i.e. F-16 fighter aircraft to perform a high angle of attack maneuver) to check the controller efficiency. Fighter aircraft need to be able to make fast and complex maneuvers (that exploit strongly nonlinear dynamics) to be able to maintain air superiority. However, such aggressive maneuvers require strong coordination between the actions to avoid destabilizing the system. A quantitative analysis from comparison with the standard MPC approach shows the practical utility of the proposed approach

Characterization of Non-Invasively Induced Post-Traumatic Osteoarthritis in Mice

The pathophysiology of post-traumatic arthritis (PTOA) is not fully understood. This study used non-invasive repetitive mechanical loading (ML) mouse models to study biochemical, biomechanical, and pain-related behavioral changes induced in mice. Mouse models reflected the effects of the early stages of PTOA in humans. For the PTOA model, cyclic comprehensive loading (9N) was applied to each mouse’s left knee joint. ML-induced biochemical and molecular changes were analyzed after loading completion. Cartilage samples were examined using gene expression analysis. Tissue sections were used in subsequent OA severity scoring. Biomechanical features and pain-related behavior were studied after 24 h and three weeks post-ML sessions to examine the development of PTOA. The loaded left knee joint showed a greater ROS/RNS signal than the right knee, which was not loaded. There was a significant increase in cartilage damage and MMP activity in the mechanically loaded joints relative to non-loaded control knee joints. Similarly, we found a difference in the viscoelastic tangent, which highlights significant changes in mechanical properties. Biochemical analyses revealed significant increases in total NO, caspase-3 activity, H2O2, and PGE2 levels. Gene expression analysis highlighted increased catabolism (MMP-13, IL-1β, TNF-α) with a concomitant decrease in anabolism (ACAN, COL2A1). Histopathology scores clearly indicated increases in OA progression and synovitis. The gait pattern was significantly altered, suggesting signs of joint damage. This study showed that biomechanical, biochemical, and behavioral characteristics of the murine PTOA groups are significantly different from the control group. These results confirm that the current mouse model can be considered for translational PTOA studies

Fracture Healing in Aging: Improving Angiogenesis

BACKGROUND: With an aging world population, there is an increased risk of fracture and impaired fracture healing. Enhancement of angiogenesis is one potential mechanism for improved fracture healing. The question then becomes: How do therapeutic targets improve these angiogenic and vasculitic conditions to facilitate successful fracture union? The current therapy, bone morphogenetic protein 2 (BMP-2), while successful in promoting fracture union, presents with several potential side effects, including excess bone growth and an increased risk of developing cancer. We hypothesize that thrombopoietin (TPO) may serve as a novel therapeutic modality for improved angiogenesis and fracture union. Here we characterize and stimulate endothelial cells (ECs) with TPO in vitro. OBJECTIVE: We hypothesize that thrombopoietin (TPO) may serve as a novel therapeutic modality for improved angiogenesis and fracture union. METHODS: Five young (3 month-old) and 5 old (22-24 month-old) C57BL/6 mice were euthanized and bone marrow was collected from the tibia and humeri for EC isolation. Additionally, five young mice underwent a 2 mm femoral diaphyseal defect surgery. Three weeks post-surgery mice were euthanized and bone marrow from the ipsilateral and contralateral tibia as well as the humeri were collected and ECs isolated. All ECs were assessed for vessel-like formation and proliferation. All in vitro studies were completed at least 3 times with triplicate samples. Statistical analyses were performed using a two-way ANOVA with Tukey’s post-hoc testing. All procedures were approved by the Indiana University IACUC. RESULTS: In vitro characterization of ECs showed impaired vessel-like formation, branch length, number of nodes, mesh area, and proliferation in old ECs compared to young ECs. ECs isolated from the ipsilateral tibia of mice undergoing a SBD surgery had impaired ECs vessel-like parameters and proliferation compared to ECs from the contralateral tibia. Finally, treatment of old ECs with TPO improved vessel-like parameters and proliferation compared to untreated cells. CONCLUSIONS: Although preliminary, our results confirm that EC proliferation and vessel formation are impaired in aging and in the ipsilateral tibia of mice, which underwent a femoral SBD surgery. Although BMP-2 is used by orthopaedic surgeons for bone healing, its use is not without side effects, leaving researchers to investigate alternative treatments. We have previously shown that TPO is effective for bone healing. Here we show that TPO improves vessel formation in aged ECs, and therefore, TPO may improve angiogenesis and fracture healing in old mice, which is currently under investigation

Type 2 Diabetes-Driven Alterations in Bone Healing and Angiogenesis

INTRODUCTION: Two out of five U.S. citizens born after 2014 are expected to develop type 2 diabetes (T2D). T2D patients are at increased risk for fracture and impaired fracture healing, including: increased frequency of partial union, delayed union, or nonunion. These outcomes can in part be explained by T2D-mediated physiological and structural changes in bone; most prominently, compromised microvascular performance, which negatively impacts angiogenesis necessary for bone regeneration. Currently, to enhance bone healing in nonunion, the only FDA-approved biological treatment is the use of bone morphogenetic protein-2 (BMP-2). However, BMP-2 does not always achieve union, has adverse side effects, and may not be optimal for overcoming the T2D-specific impairments to bone healing. OBJECTIVE: In this study, we aimed to characterize the mechanisms by which T2D impairs bone healing and hypothesize that this effect is mediated by impairments in angiogenesis and endothelial cell proliferation and function. METHODS: Using Tie2-CreER;Td-Tomato mice (Tie2CreERT+), we established a high fat diet (HFD)-induced T2D mouse model to compare with low fat diet (LFD)-fed mice. Mice underwent glucose tolerance testing, insulin tolerance testing, and echoMRI to confirm the T2D-like metabolic phenotype. They were then subjected to a femoral critical-size defect surgery and were treated with either saline or BMP-2. 60 mice were allocated to each diet and experimental treatment group. Healing of the defect was assessed by X-rays. Additionally, bone marrow-derived endothelial cells (BMECs) were collected from the surgically treated mice to assess changes in endothelial colony and tube formation in vitro. Statistical analyses were performed with a two-way ANOVA and a Tukey post-hoc test. All procedures completed were approved by the Indiana University School of Medicine Institutional Animal Care and Use Committee. RESULTS: Our results showed that after 12 weeks, HFD mice acquired a T2D-like metabolic phenotype. X-ray imaging revealed that fracture healing was impaired in the HFD mice, even with the administration of BMP-2. The isolation of BMECs was confirmed by visualization of fluorescent Tie2+ cells. Unexpectedly, in vitro tube formation assays indicated that HFD improved vessel-like formation properties. BMP-2 treatment appeared to improve some vessel-like formation properties compared to control treatment. CONCLUSIONS: Further data will need to be collected to better characterize differences in bone healing and to analyze angiogenesis in the healing femurs. Still, these data are significant as they reveal the mechanisms by which T2D impairs bone healing and demonstrate the important difference between examining endothelial cells in vitro vs. in vivo. Future investigations will examine if thrombopoietin, which our group has previously shown to improve both fracture healing and angiogenesis, may be a more effective treatment than BMP-2 in this model