scholarly journals Iterative Learning Method for In-Flight Auto-Tuning of UAV Controllers Based on Basic Sensory Information

2019 ◽  
Vol 9 (4) ◽  
pp. 648 ◽  
Author(s):  
Wojciech Giernacki
Keyword(s):  
Control Systems ◽  
Performance Index ◽  
High Efficiency ◽  
Search Algorithm ◽  
Low Cost ◽  
Sensory Information ◽  
Learning Method ◽  
Comprehensive Description ◽  
Auto Tuning ◽  
The Impact

With an increasing number of multirotor unmanned aerial vehicles (UAVs), solutions supporting the improvement in their precision of operation and safety of autonomous flights are gaining importance. They are particularly crucial in transportation tasks, where control systems are required to provide a stable and controllable flight in various environmental conditions, especially after changing the total mass of the UAV (by adding extra load). In the paper, the problem of using only available basic sensory information for fast, locally best, iterative real-time auto-tuning of parameters of fixed-gain altitude controllers is considered. The machine learning method proposed for this purpose is based on a modified zero-order optimization algorithm (golden-search algorithm) and bootstrapping technique. It has been validated in numerous simulations and real-world experiments in terms of its effectiveness in such aspects as: the impact of environmental disturbances (wind gusts); flight with change in mass; and change of sensory information sources in the auto-tuning procedure. The main advantage of the proposed method is that for the trajectory primitives repeatedly followed by an UAV (for programmed controller gains), the method effectively minimizes the selected performance index (cost function). Such a performance index might, e.g., express indirect requirements about tracking quality and energy expenditure. In the paper, a comprehensive description of the method, as well as a wide discussion of the results obtained from experiments conducted in the AeroLab for a low-cost UAV (Bebop 2), are included. The results have confirmed high efficiency of the method at the expected, low computational complexity.

scholarly journals The Impact and Empirical Analysis of the Development Level of E-commerce Industry on China’s Export Trade

2021 ◽  
Vol 235 ◽  
pp. 02046
Author(s):  
Chun Feng ◽  
Fei Lei ◽  
Zhijun Luo
Keyword(s):  
High Efficiency ◽  
Positive Impact ◽  
Low Cost ◽  
Status Quo ◽  
Export Trade ◽  
Empirical Methods ◽  
Existing Problems ◽  
Development Level ◽  
The Status ◽  
The Impact

With its advantages of low cost and high efficiency, e-commerce is not only favored by ordinary consumers, but also effectively promotes SMEs to find business opportunities and win the market. This article starts with the development scale of China’s e-commerce industry and the status quo of export trade, and measures the overall index of China’s e-commerce industry development level from 2008 to 2018 through empirical methods to analyze its impact on China’s export trade. The results show that the development level of the e-commerce industry has a significant positive impact on China’s export trade. Finally, it analyzes the existing problems in the development of China’s e-commerce industry.

scholarly journals Economics of an Additive Manufactured Heat Exchanger for Concentrating Solar Power

2022 ◽  
Author(s):  
Tracey Ziev ◽  
Erfan Rasouli ◽  
Ines Noelly-Tano ◽  
Ziheng Wu ◽  
Srujana Yarasi Rao ◽  
...  
Keyword(s):  
High Efficiency ◽  
Solar Power ◽  
Cost Model ◽  
Low Cost ◽  
Operating Conditions ◽  
Concentrated Solar Power ◽  
Future Technologies ◽  
The Cost ◽  
Alternative Current ◽  
The Impact

Developing low cost, high efficiency heat exchangers (HX) for application in concentrated solar power (CSP) is critical to reducing CSP costs. However, the extreme operating conditions in CSP systems present a challenge for typical high efficiency HX manufacturing processes. We describe a process-based cost model (PBCM) to estimate the cost of fabricating an HX for this application using additive manufacturing (AM). The PBCM is designed to assess the effectiveness of different designs, processes choices, and manufacturing innovations to reduce HX cost. We describe HX design and AM process modifications that reduce HX cost from a baseline of$780/kW-thto$570/kW-th. We further evaluate the impact of alternative current and potential future technologies on HX cost, and identify a pathway to further reduce HX cost to$270/kW-th.

scholarly journals Performance Index: A Simple Selection Method of Appropriate Energy Storage for Specific Application

2018 ◽  
Vol 171 ◽  
pp. 01002
Author(s):  
Hussein Ibrahim ◽  
Mazen Ghandour ◽  
Sabine Saad
Keyword(s):  
Energy Storage ◽  
Power Systems ◽  
Performance Index ◽  
High Efficiency ◽  
Low Cost ◽  
Storage Devices ◽  
Renewable Power ◽  
Storage Methods ◽  
Simple Selection ◽  
Term Storage

The efficiency and cost of renewable power systems using intermittent resources could significantly be improved by developing low cost, high efficiency and more sustainable energy storage systems. There are various types of storage methods, some of which are already in use, while others are still in development. A comparison study between energy storage options is presented in this paper. We have taken a look at the main characteristics of the different electricity storage techniques and their field of application (permanent or portable, long-or short-term storage, maximum power required, etc.). These characteristics will serve to make comparisons in order to determine the most appropriate technique for each type of application. Based the results obtained in this study, a “performance index” have been determined for each storage technology in order to facilitate the comparison between the different storage devices.

scholarly journals Influence of Prescribed Burning on a Pinus nigra subsp. Laricio Forest: Heat Transfer and Tree Vitality

Forests ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 915
Author(s):  
Lila Ferrat ◽  
Frédéric Morandini ◽  
Gauthier Lapa
Keyword(s):  
Heat Transfer ◽  
Prescribed Burning ◽  
High Efficiency ◽  
Low Cost ◽  
Fire Spread ◽  
Pinus Nigra ◽  
Critical Threshold ◽  
Long Term Effects ◽  
Tree Vitality ◽  
The Impact

Surface fuel removal is crucial to facilitate the mitigation of severe fires in forests. Prescribed burning is often used by forest managers, thanks to its low cost and high efficiency in hard-to-reach areas. The determination of heat transfer between fires and trees has rarely been carried out on living species and consequently, their long-term effects on tree physiology are still not fully understood. In this study, a multidisciplinary approach was conducted to evaluate the impact of a late spring (June) prescribed burning on a Mediterranean pine forest (Pinus nigra subsp. laricio). The surface fuels consisted of a 656 g m−² needle litter, mixed with a few scattered living herbaceous strata. During the fire spread, measurements of the inner and outer trunk temperatures were made at the base of 12 trees with an average bark thickness of 19.4 ± 7.0 mm. The fireline intensity and flame residence time were in the range of 110–160 kW m−1 and 220–468 s, respectively. Despite a maximum heating rate at the cambial area of 4.37 °C min−1, the temperature of these tissues remained below 60 °C, a critical threshold above which thermal damage will occur. In addition, prior- and post-fire physiological monitoring was performed over a long time period (2.5 years) on 24 trees, using sap flow, chlorophyll fluorescence and gas exchange measurements. All parameters remain highly correlated and indicate that the burned trees did not suffer physiological damage. Moreover, drought resistance strategies were not altered by the prescribed burning. The thermal insulation capability of the bark allowed the functional tissues to experience low heat stress that did not affect tree vitality.

scholarly journals An Improved Single-Epoch Attitude Determination Method for Low-Cost Single-Frequency GNSS Receivers

2021 ◽  
Vol 13 (14) ◽  
pp. 2746
Author(s):  
Xinzhe Wang ◽  
Yinbin Yao ◽  
Chaoqian Xu ◽  
Yinzhi Zhao ◽  
Huan Zhang
Keyword(s):  
Degrees Of Freedom ◽  
High Efficiency ◽  
Attitude Determination ◽  
Search Algorithm ◽  
Low Cost ◽  
Single Frequency ◽  
Baseline Length ◽  
Short Baseline ◽  
Cycle Slips ◽  
Ambiguity Fixing

GNSS attitude determination has been widely used in various navigation and positioning applications, due to its advantages of low cost and high efficiency. The navigation positioning and attitude determination modules in the consumer market mostly use low-cost receivers and face many problems such as large multipath effects, frequent cycle slips and even loss of locks. Ambiguity fixing is the key to GNSS attitude determination and will face more challenges in the complex urban environment. Based on the CLAMBDA algorithm, this paper proposes a CLAMBDA-search algorithm based on the multi-baseline GNSS model. This algorithm improves the existing CLAMBDA method through a fixed geometry constraint among baselines in the vehicle coordinate system. A fixed single-baseline solution reduces two degrees of freedom of vehicle rigid body, and a global minimization search for the ambiguity objective function in the other degree of freedom is conducted to calculate the baseline vector and its Euler angles. In addition, in order to make up for the shortcomings of short baseline ambiguity in complex environments, this paper proposes different validation strategies. Using three low-cost receivers (ublox M8T) and patch antennas, static and dynamic on-board experiments with different baseline length set-ups were carried out in different environments. Both the experiments prove that the method proposed in this paper has greatly improved the ambiguity fixing performance and also the Euler angle calculation accuracy, with an acceptable calculation burden. It is a practical vehicle-mounted attitude determination algorithm.

scholarly journals Numerical Analysis on Erosion and Optimization of a Blast Furnace Main Trough

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 4851
Author(s):  
Hao Yao ◽  
Huiting Chen ◽  
Yao Ge ◽  
Han Wei ◽  
Ying Li ◽  
...  
Keyword(s):  
Blast Furnace ◽  
High Efficiency ◽  
Low Cost ◽  
Continuous Production ◽  
Hot Metal ◽  
Main Trough ◽  
Impact Position ◽  
Refractory Life ◽  
Volume Method ◽  
The Impact

The main trough of a blast furnace (BF) is a main passage for hot metal and molten slag transportation from the taphole to the torpedo and the slag handling. Its appropriate working status and controlled erosion ensure a safe, stable, high-efficiency and low-cost continuous production of hot metal. In this work, the tapping process of a main trough of a BF in the east of China was numerically studied with the help of a CFD library written in C++, called OpenFOAM, based on the use of the Finite Volume Method (FVM). The results show that turbulence intensity downstream of the hot metal impact position becomes weaker and the turbulence area becomes larger in the main trough. During the tapping, thermal stress of wall refractory reaches the maximum value of 1.7 × 107 Pa at the 4 m position in the main trough. Furthermore, baffles in the main trough placed between 5.8 m and 6.2 m were found to control and reduce the impact of the turbulence on the refractory life. The metal flowrate upstream of the baffles can be decreased by 6%, and the flow velocity on the upper sidewall and bottom wall decrease by 9% and 7%, respectively, compared with the base model. By using baffles, the minimum fatigue life of the refractory in the main trough increases by 15 tappings compared with the base model, so the period between the maintenance stops can be prolonged by about 2 days.

scholarly journals Updating the Role of Reduced Graphene Oxide Ink on Field Emission Devices in Synergy with Charge Transfer Materials

Nanomaterials ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 137 ◽  
Author(s):  
Minas Stylianakis ◽  
George Viskadouros ◽  
Christos Polyzoidis ◽  
George Veisakis ◽  
George Kenanakis ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Field Emission ◽  
Large Scale ◽  
High Efficiency ◽  
Low Cost ◽  
Field Enhancement ◽  
Field Emitter ◽  
Reduced Graphene ◽  
The Impact

Hydroiodic acid (HI)-treated reduced graphene oxide (rGO) ink/conductive polymeric composites are considered as promising cold cathodes in terms of high geometrical aspect ratio and low field emission (FE) threshold devices. In this study, four simple, cost-effective, solution-processed approaches for rGO-based field effect emitters were developed, optimized, and compared; rGO layers were coated on (a) n+ doped Si substrate, (b) n+-Si/P3HT:rGO, (c) n+-Si/PCDTBT:rGO, and (d) n+-Si/PCDTBT:PC71BM:rGO composites, respectively. The fabricated emitters were optimized by tailoring the concentration ratios of their preparation and field emission characteristics. In a critical composite ratio, FE performance was remarkably improved compared to the pristine Si, as well as n+-Si/rGO field emitter. In this context, the impact of various materials, such as polymers, fullerene derivatives, as well as different solvents on rGO function reinforcement and consequently on FE performance upon rGO-based composites preparation was investigated. The field emitter consisted of n+-Si/PCDTBT:PC71BM(80%):rGO(20%)/rGO displayed a field enhancement factor of ~2850, with remarkable stability over 20 h and low turn-on field in 0.6 V/μm. High-efficiency graphene-based FE devices realization paves the way towards low-cost, large-scale electron sources development. Finally, the contribution of this hierarchical, composite film morphology was evaluated and discussed.

Parallel Full Search Algorithm for Motion Estimation on Graphic Processing Unit

2019 ◽  
Vol 12 (4) ◽  
pp. 317-323
Author(s):  
Fatma Ezzahra Sayadi ◽  
Marwa Chouchene ◽  
Haithem Bahri ◽  
Randa Khemiri ◽  
Mohamed Atri
Keyword(s):  
Motion Estimation ◽  
Video Compression ◽  
High Performance ◽  
High Efficiency ◽  
Search Algorithm ◽  
Low Cost ◽  
Video Quality ◽  
Processing Unit ◽  
High Efficiency Video Coding ◽  
Nvidia Gpu

Background: Advances in video compression technology have been driven by everincreasing processing power available in software and hardware. Methods: The emerging High-Efficiency Video Coding (HEVC) standard aims to provide a doubling in coding efficiency with respect to the H.264/AVC high profile, delivering the same video quality at half the bit rate. Results: Thus, the results show high computational complexity. In both standards, the motion estimation block presents a significant challenge in clock latency since it consumes more than 40% of the total encoding time. For these reasons, we proposed an optimized implementation of this algorithm on a low-cost NVIDIA GPU developed with CUDA language. Conclusion: This optimized implementation can provide high-performance video encoder where the speed reaches about 85.

scholarly journals Low-Cost and Eco-Friendly Hydroxyapatite Nanoparticles Derived from Eggshell Waste for Cephalexin Removal

Separations ◽  
2022 ◽  
Vol 9 (1) ◽  
pp. 10
Author(s):  
Huda S. Alhasan ◽  
Nadiyah Alahmadi ◽  
Suhad A. Yasin ◽  
Mohammed Y. Khalaf ◽  
Gomaa A. M. Ali
Keyword(s):  
Aqueous Solutions ◽  
High Efficiency ◽  
Low Cost ◽  
Chemical Precipitation ◽  
Solution Temperature ◽  
Order Kinetic ◽  
Experimental Conditions ◽  
Removal Process ◽  
The Impact ◽  
Eggshell Waste

This work describes the hydroxyapatite nanoparticle (HAP) preparation from eggshell waste and their application as an adsorbent for Cephalexin (Ceph) antibiotic removal from aqueous solutions. Chemical precipitation with phosphoric acid was used to evaluate the feasibility of calcium oxide for HAP preparation. The structural properties of HAP were characterized by X-ray diffraction, which revealed the formation of the hydroxyapatite crystalline phase formation. In addition, transmitting electron spectroscopy showed an irregular shape with a variation in size. The impact of various experimental conditions on the removal efficiency such as the solution’s pH, contact time, HAP mass, solution temperature, and Ceph concentration were studied. Experimental data showed that HAP could remove most Ceph species from aqueous solutions within 1 h at pH = 7 with 70.70% adsorption efficiency utilizing 50 mg of the HAP. The removal process of Ceph species by HAP was kinetically investigated using various kinetic models, and the results showed the suitability of the pseudo-second-order kinetic model for the adsorption process description. Moreover, the removal process was thermodynamically investigated; the results showed that the removal was spontaneous endothermic and related to the randomness increase. The data confirmed that HAP had high efficiency in removing Ceph antibiotics from an aqueous solution.

scholarly journals Updating the Role of Reduced Graphene Oxide Ink on Field Emission Devices in Synergy with Charge Transfer Materials

2018 ◽  
Author(s):  
Minas Stylianakis ◽  
George Viskadouros ◽  
Christos Polyzoidis ◽  
George Veisakis ◽  
George Kenanakis ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Field Emission ◽  
Large Scale ◽  
High Efficiency ◽  
Low Cost ◽  
Field Enhancement ◽  
Field Emitter ◽  
Reduced Graphene ◽  
The Impact

Hydroiodic acid (HI) treated - reduced graphene oxide (rGO) ink/conductive polymeric composites are considered as promising cold cathodes in terms of high geometrical aspect ratio and low field emission (FE) threshold devices. In this study, four simple, cost-effective, solution-processed approaches for rGO-based field effect emitters were developed, optimized and compared; rGO layers were coated on a) n+ doped Si substrate, b) n+-Si/P3HT:rGO, c) n+-Si/PCDTBT:rGO and d) n+-Si/PCDTBT:PC71BM:rGO composites, respectively. The fabricated emitters were optimized by tailoring the concentration ratios of their preparation and field emission characteristics. In a critical composite ratio, FE performance was remarkably improved compared to the pristine Si, as well as n+-Si/rGO field emitter. In this context, the impact of various materials, such as polymers, fullerene derivatives, as well as different solvents on rGO function reinforcement and consequently on FE performance upon rGO-based composites preparation was investigated. The field emitter consisted of n+-Si/PCDTBT:PC71BM(80%):rGO(20%)/rGO displayed a field enhancement factor of ∼2850, with remarkable stability over 20h and low turn-on field in 0.6V/μm. High-efficiency graphene-based FE devices realization paves the way towards low-cost, large-scale electron sources development. Finally, the contribution of this hierarchical, composite film morphology was evaluated and discussed.

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