This paper presents a solution for the formation flight problem for multiple unmanned aerial vehicles (UAVs) cooperating to execute a required mission. Learning Based Model Predictive Control (LBMPC) is implemented on the team of UAVs in order to accomplish the required formation. All flight simulations respect Reynold's rules of flocking to avoid UAV collisions with nearby flockmates, match the team members velocity and stay close to each other during the formation. The main contribution of this paper lies in the application of LBMPC to solve the problem of formation for an autonomous team of UAVs. The proposed solution is theoretically, by the application of analysis to the problem, demonstrated to be stable. Moreover, simulations support the findings of the paper. The main contributions of this paper are the proposed LBMPC formulation for formation of vehicles with uncertainty in their models, and the theoretical analysis of the solution. 相似文献
Viscous flow simulations are usually based on the Navier–Stokes equations representing the balance of mass, momentum, and energy. For many high Reynolds number flows, the viscous effects are only limited to small regions in the neighborhood of solid surfaces and in the wakes. We present here a zonal formulation with a reduced system of equations in the outer inviscid flow region. As in part I of this work, the velocity components are calculated from a generalized form of the Cauchy–Riemann equations with non-vanishing vorticity only in the inner region, where the governing equations including the viscous terms are solved. The viscous effects are transferred to the Cauchy–Riemann equations through a forcing function (vorticity), and the process is repeated until convergence. Preliminary results are presented and compared to standard Navier–Stokes calculations for two and three dimensional flow problems. 相似文献
This paper describes the design of a low cost, low-power ZigBee receiver for wireless sensor networks. The receiver consists of a low-noise amplifier, a pair of down-conversion mixers, and a pair of variable-gain low-pass filters. The LNA has a single-ended input, eliminating the need for an off-chip balun, a differential output, allowing it to drive a double-balanced mixer, and it uses noise cancellation to improve its noise performance. The mixers are double-balanced passive mixers to improve the receiver linearity and decrease its power consumption and flicker noise. Finally, the filter is a third-order Butterworth Gm-C filter with a variable input transconductor to provide gain programmability for the receiver. The design is made using 130 nm CMOS technology with 1.2 V supply. Simulation results show that the receiver can achieve a sensitivity level of −97 dBm while consuming only 6 mA. 相似文献
Target delivery and controlled release of the chemopreventive drug sulindac that possesses low water solubility present a
great challenge for its pharmaceutical industry. Here, we offered an advanced nanomatrix formulation system of sulindac based
on layered double hydroxide materials. The X-ray analysis and infrared spectroscopy confirmed the incorporation of sulindac
into the gallery of the layered double hydroxides. The incorporation ratios of sulindac were recorded to be 45, 31 and 20
for coprecipitation, anion-exchange and reconstruction techniques, respectively. The scanning electron microscopy showed a
nanomatrix-structure of ~50 nm. The release studies of sulindac-nanomatrix showed a 96% controlled release at the small intestine
solution during 3 h(s), indicating an enhancement in the dissolution profile of sulindac after the matrix formation. The layered
structure of the matrix supplied sulindac with a well-ordered structure and a relatively hydrophobic microenvironment that
controlled the guest hydrolysis and reactivity during the release process. The laminar structure of layered double hydroxides
offered a safe preservation for sulindac against photodecarboxylation, and enhanced the drug thermal stability from 190 to
230° C. The ionic electrostatic interaction of sulindac through its acidic group with layered double hydroxides demolished
the gastrointestinal ulceration. 相似文献
To describe the history of Kool''s music‐themed promotions and analyse the role that music played in the promotion of the brand.
Methods
Analysis of previously secret tobacco industry documents, legal documents, and promotional materials.
Results
Brown & Williamson started Kool sponsorship of musical events in 1975 with Kool Jazz concerts. Music was considered to be an effective marketing tool because: (1) music helped consumers make emotional connections with the brand; (2) music concerts were effective for targeted marketing; (3) music tied together an integrated marketing campaign; and (4) music had potential to appeal widely to a young audience. Brown & Williamson''s first music campaigns successfully targeted young African‐American male audiences. Subsequent campaigns were less effective, exploring different types of music to achieve a broader young adult appeal.
Conclusions
This case study suggests Brown & Williamson used music most successfully for targeted marketing, but they failed to develop a wider audience using music because their attempts lacked consistency with the Kool brand''s established identity. The 2004 “Kool Mixx” campaign both returned to Brown & Williamson''s historic practice targeting young African‐American males, and also exploited a musical genre with much more potential to bring Kool more universal appeal, as hip‐hop music is increasingly popular among diverse audiences. Tobacco control efforts led by African‐American community activists to oppose these marketing strategies should continue; expanding these coalitions to include the hip‐hop community may further increase their effectiveness. 相似文献
A substantial amount of textual data is present electronically in several languages. These texts directed the gear to information redundancy. It is essential to remove this redundancy and decrease the reading time of these data. Therefore, we need a computerized text summarization technique to extract relevant information from group of text documents with correlated subjects. This paper proposes a language-independent extractive summarization technique. The proposed technique presents a clustering-based optimization technique. The clustering technique determines the main subjects of the text, while the proposed optimization technique minimizes redundancy, and maximizes significance. Experiments are devised and evaluated using BillSum dataset for the English language, MLSUM for German and Russian and Mawdoo3 for the Arabic language. The experiments are evaluated using ROUGE metrics. The results showed the effectiveness of the proposed technique compared to other language-dependent and language-independent summarization techniques. Our technique achieved better ROUGE metrics for all the utilized datasets. The technique accomplished an F-measure of 41.9% for Rouge-1, 18.7% for Rouge-2, 39.4% for Rouge-3, and 16.8% for Rouge-4 on average for all the dataset using all three objectives. Our system also exhibited an improvement of 26.6%, 35.5%, 34.65%, and 31.54% w.r.t. The recent model contributed in the summarization of BillSum in terms of ROUGE metric evaluation. Our model’s performance is higher than the compared models, especially in the metric results of ROUGE_2 which is bi-gram matching. 相似文献
One of the ongoing issues with time fractional diffusion models is the design of efficient high-order numerical schemes for the solutions of limited regularity. We construct in this paper two efficient Galerkin spectral algorithms for solving multi-dimensional time fractional advection–diffusion–reaction equations with constant and variable coefficients. The model solution is discretized in time with a spectral expansion of fractional-order Jacobi orthogonal functions. For the space discretization, the proposed schemes accommodate high-order Jacobi Galerkin spectral discretization. The numerical schemes do not require imposition of artificial smoothness assumptions in time direction as is required for most methods based on polynomial interpolation. We illustrate the flexibility of the algorithms by comparing the standard Jacobi and the fractional Jacobi spectral methods for three numerical examples. The numerical results indicate that the global character of the fractional Jacobi functions makes them well-suited to time fractional diffusion equations because they naturally take the irregular behavior of the solution into account and thus preserve the singularity of the solution.
Starting with evidence that United Kingdom Continental Shelf oil and gas companies have benefitted very disproportionately from the recent period of extraordinarily high oil prices, this paper traces the history of this weakness in the UK’s petroleum fiscal regime. Evidence is provided that the progressive relaxations in the UK’s petroleum fiscal regime in 1983, 1987–1988 and 1993 were: largely unnecessary to stimulate the development of new, smaller, ‘marginal’ fields; misguided in their assumption that such fields were more costly to develop than earlier counterparts or larger contemporary fields; and impotent compared with the effects of oil price movements. The paper concludes with a conceptualisation which illuminates why these failures of policy were not just random: they emerged from the UK’s ‘non-proprietorial’ stance with respect to the country’s oil and gas resources, a stance which assumes responsibility for oil company profitability and vainly tries to counter market forces at the expense of government revenues. 相似文献
Steady-state operational data from the integrated biohydrogen reactor clarifier system (IBRCS) during anaerobic treatment of glucose-based synthetic wastewater at HRT of 8 h and SRT ranging from 26 to 50 h and organic loading rates of 6.5–206 gCOD/L-d were used to calibrate and verify a process model of the system developed using BioWin. The model accurately predicted biomass concentrations in both the bioreactor and the clarifier supernatant with average percentage errors (APEs) of 4.6% and 10%, respectively. Hydrogen production rates and hydrogen yields predicted by the model were in close agreement with the observed experimental results as reflected by an APE of less than 4%, while the hydrogen content was well correlated with an APE of 10%. The successful modeling culminated in the accurate prediction of soluble metabolites, i.e. volatile fatty acids in the reactor with an APE of 14%. The calibrated model confirmed the advantages of decoupling of the solids retention time (SRT) from the hydraulic retention time (HRT) in biohydrogen production, with the average hydrogen yield decreasing from 3.0 mol H2/mol glucose to 0.8 mol H2/mol glucose upon elimination of the clarifier. Dynamic modeling showed that the system responds favorably to short-term hydraulic and organic surges, recovering back to the original condition. Furthermore, the dynamic simulation revealed that with a prolonged startup periods of 10 and 30 days, the IBRCS can be operated at an HRT of 4 h and OLR as high as 206 gCOD/L-d without inhibition and/or marked performance deterioration. 相似文献