Numerical Search Research Articles

Improving the extension–twist coupling performance of practically warpage-free laminates via layup hybridization

This article investigates whether the extension–twist and bend–twist coupling performance of practically warpage-free laminates can be improved by layup hybridization (carbon/epoxy–glass/epoxy hybrids) compared to non-hybrid (mono) laminates. We performed numerical layup search by simulating the thermal warpage, and the bend–twist and extension–twist behaviour of 4096 4-ply layup permutations. The upper limit of allowable manufacturing-induced warpage was based on the ISO2768 standard. The optimal hybrid and mono layups were selected to have the most significant coupling performance within the allowable warpage range. A mono layup achieved the maximum bend–twist performance (which does not require layup asymmetry), but layup hybridization increased the extension–twist performance by more than 30% in the practically warpage-free range. The numerical results were validated through 3D scanning and 3D digital image correlation–aided mechanical tests. We concluded that layup hybridization can significantly improve the extension–twist performance of realistically usable composite laminates with negligible thermal warpage.

Structural control of high-rise buildings subjected to multi-hazard excitations using inerter-based vibration absorbers

High-rise buildings located in strong wind and earthquake-prone regions are exposed to multiple hazards that must be properly considered to prevent considerable socio-economic losses. In the present study, the Tuned Mass Damper-Inerter (TMDI) is adopted for the structural control of high-rise buildings under wind and earthquake excitations by exploiting its inherent multiple-mode control effects. A generalized multi-degree-of-freedom (MDOF) model of TMDI-controlled structure is established first and compared with the commonly-adopted generalized single-degree-of-freedom (SDOF) model. Analytical investigation on the multiple-mode control effects of TMDI demonstrates that the damping effects weighted by mode coordinate differences at two terminals of TMDI are mainly responsible for its multiple-mode control effects. Based on a real high-rise building project, analysis errors induced by the generalized SDOF model against the more accurate generalized MDOF model are quantified by a comprehensive Monte Carlo simulation, which suggests the necessity of adopting numerical search for parametric design of TMDI under most circumstances. Therefore, the parameters of TMDI and its two competitors, i.e., Multi-Tuned Mass Damper (MTMD) and Multi-Tuned Mass Damper-Inerter (MTMDI), are optimized using a genetic algorithm, assuming both wind- and earthquake-induced responses as performance objectives. Time and frequency domain analyses demonstrate the efficiency of utilizing the multiple-mode control effects of a single TMDI for multi-hazard design. The trend of the equivalent damping ratio of TMDI-controlled structure on an arbitrary mode is analyzed to identify the design parameters affecting most the TMDI multiple-mode control effect at last.

Women's Studies Archive: Rare Titles from the American Antiquarian Society, 1820‐1922

Women's Studies Archive: Rare Titles from the American Antiquarian Society, 1820‐1922 provides literature by female authors on the American woman's experience in the nineteenth and twentieth centuries. It is the third database in Gale's Women's Studies Archive, which is only one of a number of Gale Primary Sources collections. It contains more than one million pages of works from the American Antiquarian Society, all authored or edited by women. The works available here are drawn from the American Antiquarian Society's library collections and cover a wide variety of nonfiction subjects and fiction genres.This database is relatively easy to navigate, though the numerous available search and browse functions may prove confusing to some. Despite this relatively minor complication, this resource offers a broad and varied range of materials from female authors in the time period indicated above. This is not a subscription database; instead, it must be purchased. The price, based on full-time enrollment (FTE), can range from $22,080 to $27,600. The licensing agreement for this database is too long, overly detailed, and sometimes repetitive, but in most ways is average in its composition.

On the continuous Zauner conjecture

In a recent paper by S. Pandey, V. Paulsen, J. Prakash, and M. Rahaman, the authors studied the entanglement breaking quantum channels $\Phi_t:\mbb{C}^{d\times d} \to \mbb{C}^{d \times d}$ for $t \in [-\frac{1}{d^2-1}, \frac{1}{d+1}]$ defined by $\Phi_t(X) = tX+ (1-t)\tr(X) \frac{1}{d}I$. They proved that Zauner's conjecture is equivalent to the statement that entanglement breaking rank of $\Phi_{\frac{1}{d+1}}$ is $d^2$. The authors made the extended conjecture that $\ebr(\Phi_t)=d^2$ for every $t \in [0, \frac{1}{d+1}]$ and proved it in dimensions 2 and 3. In this paper we prove that for any $t \in [-\frac{1}{d^2-1}, \frac{1}{d+1}] \setminus\{0\}$ the equality $\ebr(\Phi_t)=d^2$ is equivalent to the existence of a pair of informationally-complete unit-norm tight frames $\{|x_i\ra\}_{i=1}^{d^2}, \{|y_i\ra\}_{i=1}^{d^2}$ in $\mbb{C}^d $ which are mutually unbiased in the following sense: for any $i\neq j$ it holds that $|\la x_i|y_j\ra|^2 = \frac{1-t}{d}$ and $|\la x_i|y_i\ra|^2 = \frac{t(d^2-1)+1}{d}$. Moreover, it follows that $|\la x_i|x_j\ra\la y_i|y_j\ra|=|t|$ for $i\neq j$. However, our numerical searches for solutions were not successful in dimensions 4 and 5 for values of $t$ other than $0$ or $\frac{1}{d+1}$.

Do Internet Search Data Help Forecast Air Passenger Demand? Evidence From China's Airports.

Before making travel plans, people often use the Internet to collect relevant information to help themselves make better decisions. Among the numerous information search channels, Internet search engine is used by the vast number of travelers because of its low cost and high efficiency. To a large extent, Internet search behavior is the external manifestation of users’ psychological activities, reflecting their concerns, needs and preferences. Therefore, Internet search data can reflect the air passenger demand information to a certain extent. In this manuscript, a novel decomposition ensemble model is proposed to discuss the role of Internet search data in air passenger demand forecasting. In the empirical study, the relevant data of Shanghai Pudong International Airport and Beijing Capital International Airport are taken as samples. The results show that the proposed forecasting model can integrate the advantages of decomposition-ensemble strategy and deep learning algorithm, and achieve more accurate and reliable prediction results than all benchmark models. This further indicates that adding Internet search data into the forecasting model can effectively improve the prediction performance of air passenger demand, and can provide scientific and reliable decision support for air transport management.

And optimal designs of tuned inerter dampers for base motion excited structures with inherent damping

Tuned inerter damper (TID) has recently gained increasing attention as a new structural control mechanism for seismic protection of structures. Currently, theoretical investigations are undertaken by researchers to reveal its fundamentals and to understand its underline principles in altering the structural performances of structures against dynamic loadings. However, the comprehensive study of optimization design of TID for undamped structures is lacking and the majority of the research focuses on the optimization of TID for structures without any damping. This research evaluates the and optimal designs of TIDs on the structures with damping. Using SDOF structure as an example, the frequency response function of the system equipped with TID underground motion excitation is obtained. The and designs of TID for structures without damping are derived considering various response parameters using analytical method. A numerical search method is utilized for the and designs of TID for structures with damping; meanwhile, a set of explicit formulae are obtained by curve-fitting for convenience in the application. Finally, the relative motion response of the inerter is explored, and an optimal design formula of TID which can reduce the displacements of primary mass and inerter simultaneously, is proposed.

Low-Thrust Orbit Dynamics and Periodic Trajectories in the Earth–Moon System

This study employs the circular restricted three-body problem (CR3BP) as the dynamical framework, for the purpose of investigating low-thrust orbit dynamics in the Earth–Moon system. First, the effect of low thrust on some dynamical structures that exist in the CR3BP is analyzed. Low-thrust capture and escape dynamics in the proximity of the Moon is investigated for preliminary mission analysis. Then, low-thrust periodic orbits—with potential practical application—are detected. To do this, the theorem of mirror trajectories, proven 6 decades ago, is extended to low-thrust trajectories. This represents the theoretical premise for the definition and use of a numerical search methodology based on modified Poincaré maps. This approach leads to identifying several low-thrust periodic orbits in the Earth–Moon system that are infeasible if only unpowered paths are considered. Two possible applications of low-thrust periodic orbits are described: (a) cycling transfer trajectories that connect Earth and Moon continuously, and (b) non-Keplerian periodic paths about the Moon, with potential use as operational orbits for satellite constellations.

On the Search for Low W0

AbstractThe magnitude of the vacuum expectation value of the Gukov‐Vafa‐Witten superpotential plays a central role in the phenomenology of type IIB flux compactifications. Recent analytical constructions have shown that perturbatively flat vacua can be used to obtain very low values of . We present systematic algorithms to carry out exhaustive numerical searches for such vacua. We also analyse them in the statistical context, as part of the entire ensemble of type IIB flux vacua at low . Our preliminary analysis indicates that these perturbatively flat vacua are statistically sparse in the whole set of vacua at low as calculated by Denef and Douglas. Two‐moduli examples are used to illustrate these more general findings in specific settings. We find that these simple (two moduli) cases are good examples for existence proofs but they do not feature a large statistical tuning freedom for phenomenological applications.

Do tides destabilize Trojan exoplanets?

One outstanding problem in extrasolar planet studies is why no co-orbital exoplanets have been found, despite numerous searches among the many known planetary systems, many of them in other mean-motion resonances. Here we examine the hypothesis that dissipation of energy by tides in Trojan planets is preventing their survival.The Appendix of this paper generalizes the conventional theory of tides to include tidal forces independent of dissipation, as well as the effects of one body on tides raised by another. The main text applies this theory to a model system consisting of a primary of stellar mass, a secondary of sub-stellar mass in a circular orbit about the primary, and a much lighter Trojan planet librating with small amplitude about an equilateral point of the system.Next, we linearize the equations of motion about the Trojan points, including the tidal forces, and solve for the motion of the Trojan. The results indicate that tides damp out the Trojan’s motion perpendicular to the orbital plane of the primary and secondary, as well as its epicycles due to its eccentricity; but they pump up the amplitude of its tadpole librations exponentially. We then verify our analytic solutions by integrating the non-linearized equations of motion numerically for several sample cases. In each case, we find that the librations grow until the Trojan escapes its libration, which leads to a close encounter with either the primary or the secondary.

A Template Model Explains Jerboa Gait Transitions Across a Broad Range of Speeds.

For cursorial animals that maintain high speeds for extended durations of locomotion, transitions between footfall patterns (gaits) predictably occur at distinct speed ranges. How do transitions among gaits occur for non-cursorial animals? Jerboas (Jaculus) are bipedal hopping rodents that frequently transition between gaits throughout their entire speed range. It has been hypothesized that these non-cursorial bipedal gait transitions are likely to enhance their maneuverability and predator evasion ability. However, it is difficult to use the underlying dynamics of these locomotion patterns to predict gait transitions due to the large number of degrees of freedom expressed by the animals. To this end, we used empirical jerboa kinematics and dynamics to develop a unified spring Loaded Inverted Pendulum model with defined passive swing leg motions. To find periodic solutions of this model, we formulated the gait search as a boundary value problem and described an asymmetrical running gait exhibited by the jerboas that emerged from the numerical search. To understand how jerboas change from one gait to another, we employed an optimization approach and used the proposed model to reproduce observed patterns of jerboa gait transitions. We then ran a detailed numerical study of the structure of gait patterns using a continuation approach in which transitions are represented by bifurcations. We found two primary mechanisms to increase the range of speeds at which gait transitions can occur. Coupled changes in the neutral leg swing angle alter leg dynamics. This mechanism generates changes in gait features (e.g., touchdown leg angle and timings of gait events) that have previously been shown to induce gait transitions. This mechanism slightly alters the speeds at which existing gait transitions occur. The model can also uncouple the left and right neutral leg swing angle, which generates asymmetries between left and right leg dynamics. New gait transitions emerge from uncoupled models across a broad range of speeds. In both the experimental observations and in the model, the majority of the gait transitions involve the skipping and asymmetrical running gaits generated by the uncoupled neutral leg swing angle mechanism. This simulated jerboa model is capable of systematically reproducing all biologically relevant gait transitions at a broad range of speeds.

3D Location Optimization for UAV-Aided Uplink/Downlink Transmissions

In this paper, we investigate the placement of an unmanned aerial vehicle (UAV) base station (BS) which serves multiple ground users (GUs). By taking into account both the uplink and downlink transmissions, we aim to optimize the 3D location of the UAV for maximizing the minimum average sum rate. The 3D location optimization problem is divided into the horizontal coordinate and the height optimization subproblems, respectively. We further apply the CVX toolbox to solve the horizontal coordinate optimization problem and transform the height optimization problem into the elevation angle optimization problem to obtain its solution. Our numerical results show that the minimum average sum rate of the proposed 3D location optimization scheme is higher than that of the numerical search (NS) based location optimization method, that of the energy-efficient maximal coverage (EEMC) based location optimization method and that of the random location method, for different distributions of GUs’ locations.

Numerical Search for a Global Solution in a Two-Mode Economy Model with an Exhaustible Resource of Hydrocarbons

Numerical Search for a Global Solution in a Two-Mode Economy Model with an Exhaustible Resource of Hydrocarbons

Social Determinant of Housing Instability and Adverse Pregnancy Outcomes: A Scoping Review.

We conducted a scoping review to examine the literature regarding pregnancy-related morbidities among birthing individuals and infants experiencing housing instability (HI). Articles were identified through electronic database searches, using numerous search terms related to pregnancy and housing. US studies published in English between 1991 and 2019 were included. Peer-reviewed qualitative and quantitative articles were synthesized and critically appraised by 2 reviewers using quality appraisal tools from the Joanna Briggs Institute. Inconsistent definitions for HI weakened the rigor of aggregate findings, and birthing individual outcomes were underreported compared with infant outcomes (n = 9 095 499 women, 11 articles). Many studies reported mental health-related outcomes among birthing individuals with HI. Study sampling approaches and lack of a standard definition of HI limit review findings, but examining this relationship is critical to understanding the effect of social determinants on birthing individual health. Future research should address the nescience regarding birthing individual outcomes in this population. Policy-level advocacy addressing social determinants must also refine policy impacting community-based prenatal programs and services for the birthing individual with HI.

Pursuer Aim Identification for an Aircraft Formation Using a Passive Sensor Without State Estimation

In a pursuit evasion scenario, a missile (pursuer) launched from the ground or the air aims to intercept an aircraft (evader) flying in formation. This article considers the problem of whether an aircraft is aimed by a missile or not, based only on the line-of-sight (LOS) measurements from an on-board passive sensor. The motion of the missile is assumed to be governed by pure proportional navigation guidance. Previous works on this problem estimate the missile’s state motion parameters, which, for a passive sensor, requires a numerical search, i.e., significant computation time, algorithm complexity and is ill-conditioned. We present a methodology that relies on the geometric relationship between the aircraft and the missile without state estimation. A plane is defined by the aircraft velocity vector and one aircraft-to-missile LOS vector, and if a second LOS vector at a subsequent time is in this plane, it is known that the missile aims at the aircraft. A coplanarity test is designed on the basis of these three vectors. We then provide a test statistic for inferring whether the airplane is aimed by the missile. An approximate distribution is used to set the threshold for detection and false alarm probabilities. Simulation results are presented for surface-to-air and air-to-air missile scenarios to illustrate the efficiency of the proposed method and compared to the state estimation method.

A MCMC-type simple probabilistic approach for determining optimal progressive censoring schemes

We present here a simple probabilistic approach for determining an optimal progressive censoring scheme by defining a probability structure on the set of feasible solutions. Given an initial solution, the new updated solution is computed within the probabilistic structure. This approach will be especially useful when the cardinality of the set of feasible solutions is large. The validation of the proposed approach is demonstrated by comparing the optimal scheme so determined with the one obtained by exhaustive numerical search.

Assessing the Stability of Slopes Using Vector-Sum-Based Numerical Manifold Method and Pattern Search Algorithm

Assessing the Stability of Slopes Using Vector-Sum-Based Numerical Manifold Method and Pattern Search Algorithm

A novel three dimensional nonlinear tuned mass damper and its application in floating offshore wind turbines

This paper proposes a novel three-dimensional non-linear tuned mass damper (3d-NTMD) to effectively mitigate three-dimensional structural responses. The 3d-NTMD consists of a mass and three pairs of springs and dash-pots configured in three axes. The resultant restoring forces are nonlinear with respected to the displacements in the three axes. While the proposed 3d-NTMD has the potential to simultaneously mitigate triaxial vibrations, the system nonlinearity complicates the optimization. A numerical search approach is adopted to determine the optimum design. The National Renewable Energy Laboratory spar floating wind turbine (FWT) model is used to evaluate the performance of the 3d-NTMD in reducing the motion of the FWT in three directions: pitch, roll and heave. To this end, an analytical model of a spar FWT with a 3d-NTMD in the spar is established. The wind loading is determined using blade element momentum method and the wave loading is calculated using JONSWAP spectrum and Morison equation. The effectiveness of the 3d-NTMD is examined under operational and parked conditions. Results show that the 3d-NTMD outperforms linear TMDs and can effectively reduce the response of the FWT in three directions. The proposed 3d-NTMD has the potential to mitigate three-dimensional vibrations of a large set of civil/mechanical systems.

An Information-Based Approach to Sustainable Eco-Communities through Climate Change Initiatives

Numerous searches conducted across the globe on Climatic Change initiatives reveal that current human discharges of atmospheric glasshouse gases are of the utmost in the record. Recent weather conditions have had extensive effects on man and ecological communities. Diverse varieties of living things have been impacted negatively by the sudden changes in their ecological habitats, irregular transformation in atmospheric conditions, movement forms, supplies and varieties interrelationships in action to ongoing climatic variation. The current trends and forces on diverse living components will continue to expand, and varieties of living things will further reduce. This study assessed recent information on the impact of ecological communities worldwide and their impacts on climate change alleviation. The data guiding this study derived from the various reports from academic articles and other related studies which citations appropriately utilise in this ongoing study. The research offers information on the capability of previous administrative methods for wetlands, wildlands and pampas lands, coastland ecological communities and farmlands to support and promote carbon accumulation and carbon drifts. The research suggested increasing collaborations with climatic variation solutions, hazard threat reduction, viable growth, and ecological and living organisms. The diverse solutions offer broader land-use methods that consider all investors' viable advantages, information, and competencies. Empirical proof regarding living organisms' relevance for sustainable ecological communities and operation, thus the broad impact of a climatic change initiative, is vividly represented in this study.

Confronting Gender Inequalities in Education Leadership: A Case of Zimbabwe

The persistence of the marginalisation of women has dominated education leadership research recently. This study examined literature on women’s education leadership and management through the lens of social justice. The study used Shields’s tenets of transformative leadership to unearth and dissect issues of gender discrimination in education leadership. As a catalyst for a recent systematic review of research on Zimbabwean women’s education leadership literature, the study reviewed 22 publications used earlier in the systematic research review. The studies were identified through numerous electronic searches following carefully defined eligibility criteria. A thematic analysis was conducted through the use of mind maps to deduce common themes. The results suggested a transformation of persistent political, institutional, structural, economic, cultural and social inequalities and human rights violations to achieve social justice in education leadership. Further research should be undertaken to examine the root causes of persistent gender imbalances and the failure of gender equity.

Utilizing AI Planning on the Edge

The convergence between AI planning techniques and the Internet of Things (IoT) can solve various operational and business challenges. However, IoT systems’ stringent requirements such as latency and scalability have introduced several challenges to execute and scale planners in cloud environments. Edge computers placed close to the IoT domain (e.g., sensors) can be leveraged for implementing planners and overcoming scalability issues. We propose a conceptual framework highlighting executing Expressive Numeric Heuristic Search Planner on distributed devices in edge networks. As a proof of concept, we develop a simulator to show the applicability and feasibility of running planners on the edge. As a case study, we simulate a waste management problem and find the optimal route for disposing of? waste bins in a city. Throughout the experiments, the user can discover insightful information regarding the planner’s applicability on the edge.