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Agricultural eco-efficiency is an important indicator used to measure agriculture’s high-quality and sustainable development. Therefore, this paper uses the EBM-Super-ML method with strong disposability of undesired output to calculate Chinese agricultural eco-efficiency and uses a geographical detector to measure the driving force of the factor. The research conclusions are mainly reflected in three aspects. Firstly, from the perspective of eco-efficiency changes, the overall mean value of agricultural eco-efficiency increased by 3.5%, and the regional heterogeneity is significant, with the fastest growth in the eastern region. Secondly, the results of driving force analysis show that the main driving factors of agricultural eco-efficiency divergence are capital inputs, total carbon emissions, labor inputs, agricultural film residues, fertilizer use, and pesticide residues, with driving forces of 0.43, 0.37, 0.34, 0.31, 0.28, and 0.20, respectively. Finally, from the perspective of eco-efficiency improvement potential, the mean value of output improvement potential is 5%, and the input factor is 7%. Among the non-desired outputs, the reduction rate of agricultural films can reach 40%. Among the input factors, labor input has the highest potential for intensive use, while agricultural machinery has a negative effect. Therefore, strengthening the development of the agricultural service industry is of great significance to improve the utilization rate of mechanical equipment and reduce the undesired output of agriculture.

Hydrogen production through alkaline water electrolysis holds great promise as a scalable solution for renewable energy storage and conversion. The development of non-precious metal-based electrocatalysts with low-overpotential for alkaline water...

A new diluted magnetic semiconductor (Sr, Na)(Zn, Mn)2Sb2 has been successfully synthesized by doping Na and Mn into the parent compound SrZn 2 Sb 2 , which has a CaAl 2 Si 2 -type crystal structure (space group P 3 ¯ m 1 , No. 164, h P 5 ) isostructural to the 122-type iron-based superconductor CaFe 2 As 2 . No magnetic ordering has been observed when only spins are doped by (Zn, Mn) substitution. Only with carriers codoped by (Sr, Na) substitution, a ferromagnetic ordering occurs below the maximum Curie temperature T C ∼9.5 K. Comparing with other CaAl 2 Si 2 -type diluted magnetic semiconductors, we will show that negative chemical pressure suppresses the Curie temperature.

Ship detection is significant and full of challenges in the field of remote sensing. The widely adopted horizontal bounding box representation is not appropriate for ubiquitous oriented ship objects. Complex backgrounds, small objects, and the dilemma of labeling ship datasets are all obstacles that further limit the successful operation of traditional methods in ship detection. In this paper, we propose a multi-task rotation detector using attention module, multi-scale feature fusion and rotation pseudo-label, namely AMR-Net. AMR-Net adds Deformable Convolution Channel Attention Block (DCCAB) to suppress background noise and highlight the foreground. Feature Pyramid Network (FPN) fuses features from different scales, which is beneficial for ship detection. We present Adaptive FPN (AFPN) to determine the optimal number of prediction layers automatically, which can reduce the disturbance of high-level detection of small objects, decrease the size of the model, and adapt to different ship datasets. To enable the detector to achieve excellent performance even when using fewer labeled data, a semi-supervised pseudo-label module is designed, namely Self-Learning Rotation Pseudo-Label (SRP). SRP allows the detector to iteratively self-learn the optimal thresholds, and use the thresholds to refine high-quality rotation pseudo-labels for retraining the model. SRP is optional. If this module is selected, the detector becomes a semi-supervised detector. Extensive both supervised and semi-supervised experiments on remote sensing public datasets HRSC2016 show the state-of-the-art performance of our detector. Experiments on DOTA further illustrate the effectiveness of AMR-Net.

To investigate the value of histogram analysis of T1 mapping and diffusion-weighted imaging (DWI) in predicting the grade, subtype, and proliferative activity of meningioma.This prospective study comprised 69 meningioma patients who underwent preoperative MRI including T1 mapping and DWI. The histogram metrics, including mean, median, maximum, minimum, 10th percentiles (C10), 90th percentiles (C90), kurtosis, skewness, and variance, of T1 and apparent diffusion coefficient (ADC) values were extracted from the whole tumour and peritumoural oedema using FeAture Explorer. The Mann-Whitney U test was used for comparison between low- and high-grade tumours. Receiver operating characteristic (ROC) curve and logistic regression analyses were performed to identify the differential diagnostic performance. The Kruskal-Wallis test was used to further classify meningioma subtypes. Spearman's rank correlation coefficients were calculated to analyse the correlations between histogram parameters and Ki-67 expression.High-grade meningiomas showed significantly higher mean, maximum, C90, and variance of T1 (p = 0.001-0.009), lower minimum, and C10 of ADC (p = 0.013-0.028), compared to low-grade meningiomas. For all histogram parameters, the highest individual distinctive power was T1 C90 with an AUC of 0.805. The best diagnostic accuracy was obtained by combining the T1 C90 and ADC C10 with an AUC of 0.864. The histogram parameters differentiated 4/6 pairs of subtype pairs. Significant correlations were identified between Ki-67 and histogram parameters of T1 (C90, mean) and ADC (C10, kurtosis, variance).T1 and ADC histogram parameters may represent an in vivo biomarker for predicting the grade, subtype, and proliferative activity of meningioma.• The histogram parameter based on T1 mapping and DWI is useful to preoperatively evaluate the grade, subtype, and proliferative activity of meningioma. • The combination of T1 C90 and ADC C10 showed the best performance for differentiating low- and high-grade meningiomas.

This study investigates the spillover effects among partisan conflict, national security policy uncertainty and tourism (i.e., tourist arrivals, exports, and stock) in the U.S. by using the TVP-VAR-based connectedness measures. Specifically, we discuss the association strength, spillover direction and dynamic linkages among the three under this framework. The results show that partisan conflict and national security policy uncertainty are net transmitters of spillovers to tourism, and those effects are more potent for inbound tourism demand than tourism stock performance. Moreover, the magnitude of spillovers among the three is time-varying and increases significantly in times of crisis, especially during the 9/11 attacks, the global financial crisis and the COVID-19 pandemic. Our results have important implications for tourism managers to develop sustainable development strategies to buffer or adapt to the uncertainty impact.

This study investigates the time-varying effects of three types of oil price shocks (oil demand, supply, and risk shock) on exchange rates by applying the time-varying parameter structural vector autoregression stochastic volatility (TVP-SVAR-SV) model. Through examining the impulse response of exchange rates to oil price shocks at different lag periods and time points, this paper contributes to the existing literature on the dynamic relationship between oil shocks and exchange rates. From the response at different lag periods, we find that oil price shocks have a significant time-varying impact on the exchange rate, among which oil demand shock has the most significant effect. The response of the exchange rate market to oil price shock shows an obvious short-term time-varying effect and is positive and negative alternately, with a certain periodicity. From the response at different time points, the time-varying effect of oil price shock on exchange rates is related to external shock, and is more intense during the global economic and political turmoil. This is the first empirical study using a novel method to examine the time-varying effects of oil price shock from different sources on exchange rates, providing investors and policy makers assistance to manage foreign exchange during global turmoil periods.

We have successfully synthesized a novel diluted magnetic semiconductor (Ca1−2x K2x )(Zn1− x Mn x )2As2 with decoupled charge and spin doping. The substitutions of (Ca2+, K+) and (Zn2+, Mn2+) in the parent compound CaZn2As2 (space group P m1 (No. 164)) introduce carriers and magnetic moments, respectively. Doping only Mn into CaZn2As2 does not induce any type of long range magnetic ordering. The ferromagnetic ordering arise can only when K+ and Mn2+ are simultaneously doped. The resulted maximum Curie temperature reaches ~7 K, and the corresponding coercive field is ~60 Oe. The transport measurements confirm that samples with K and Mn co-doping still behave like a semiconductor.

We report the effect of chemical pressure on the ferromagnetic ordering of the recently reported n-type diluted magnetic semiconductor Ba(Zn$$_{1-x}$$ 1 - x Co$$_{x}$$ x )$$_{2}$$ 2 As$$_{2}$$ 2 which has a maximum $$T_C$$ T C $$\sim$$ ∼ 45 K. Doping Sb into As-site and Sr into Ba-site induces negative and positive chemical pressure, respectively. While conserving the tetragonal crystal structure and n-type carriers, the unit cell volume shrink by $$\sim$$ ∼ 0.3$$\%$$ % with 15$$\%$$ % Sr doping, but drastically increase the ferromagnetic transition temperature by 18$$\%$$ % to 53 K. Our experiment unequivocally demonstrate that the parameters of Zn(Co)As$$_{4}$$ 4 tetrahedra play a vital role in the formation of ferromagnetic ordering in the Ba(Zn,Co)$$_{2}$$ 2 As$$_{2}$$ 2 DMS.

Feature pyramid mechanism has improved the performance of object detectors by a large margin, especially for the objects with small scale. As one of the first attempts to use pyramidal feature hierarchy, Single Shot MultiBox Detector (SSD) has largely accelerated the pipeline of detection with the competitive performance. Even if the feature pyramid mechanism is used for better detecting objects with small scale, the complex background information still misleads the network to focus on invalid areas. Image areas where small objects exist are more easily to be misjudged which influences the performance of lower-level layer in feature pyramid. In addition, a great deal of false positives may also be introduced into each pyramid layer because of the complex background. In this paper, we propose a novel method named scale pyramid attention hierarchy to better assist the SSD. The general feature pyramid detector can be guided to focus on the valid image areas as well as neglect the influence of complex background with the assist of this proposed module. Furthermore, the end-to-end training can highlight the foreground information which reduces the pressure of detectors, especially for detecting small objects. Flexible implementation makes it easily embedded in the feature pyramid mechanism. Experimental results on PASCAL VOC 2007, VOC 2012 and MS COCO confirm the effectiveness of the proposed module.

In the mission of searching and rescuing, it is often faced with the situation that the area to be searched is large and the target to be searched is small. Combined with the object detection technology, this paper proposes a method for searching drowning people. At first, we make a dataset, which contains a large number of human targets at sea. Then, we improve the Yolov3 algorithm: In the feature extraction network, we use the residual module with channel attention mechanism. In the feature fusion network, we add a bottom-up structure to the FPN structure. Moreover, in terms of loss function, we use the CIoU loss function. Finally, on the settings of the anchor box, we use a linear transformation method to deal with the anchor boxes generated by clustering algorithm. The detection accuracy of the improved algorithm for human targets at sea is 72.17%, which has a good detection effect.

To locate and identify weeds in a wheat field efficiently, an unmanned aerial vehicle (UAV) based imaging method was developed in this study.  A weed detection model based on image data through deep learning was developed and implemented.  The model uses the YOLOV3-tiny network to detect the pixel coordinates of weeds in images.  It acquires the position of weeds by converting the pixel coordinates to the geodetic coordinates.  The identified weeds were marked on the prescription map.  The algorithm was implemented and tested using a commercial DJI Phantom 3 UAV.  This study tested the performance of YOLOV3 and YOLOV3-tiny and found that YOLOV3-tiny was more suitable for mobile devices.  The performance of YOLOV3-tiny at different thresholds was tested.  The test results show that the model performs optimally when the threshold of the YOLOV3-tiny network is 0.5, under this condition, the mean Average Precision (mAP) is 72.5%, the Intersection-over-Union (IOU) is 80.12%, and the mobile device processing speed is 2FPS.  After testing and analyzing weed positioning, results show the average positioning error is10.31 cm, which is extremely small in agricultural operations.  The UAV-based weed position detection system can locate and identify weeds in the crop field at a high speed, efficiently and effectively. Keywords: UAV, deep learning, weed location, weed recognition, imaging method, target detection, Android APP DOI:  10.33440/j.ijpaa.20200301.63  Citation: Zhang R F, Wang C, Hu X P, Liu Y X, Chen S, Su B F. Weed location and recognition based on UAV imaging and deep learning. Int J Precis Agric Aviat, 2020; 3(1): 23–29.

We report the successful synthesis and characterization of a diluted magnetic semiconductor Cu2(Zn,Mn)(Sn,Al)Se4 with stannite structure. 15% of Mn doping into the quaternary semiconductor Cu2ZnSnSe4 does not induce any type of magnetic ordering. Only when Al is codoped with Mn, is ferromagnetic transition observed in Cu2(Zn,Mn)(Sn,Al)Se4. Our results demonstrate that Mn substitution for Zn introduces local moments, while Al substitution for Sn introduces carriers, respectively. Both spins and carriers are crucial in the formation of ferromagnetic ordering in Cu2(Zn,Mn)(Sn,Al)Se4.

Code Differential Global Positioning System (DGPS) is widely used in satellite navigation and positioning because of its simple algorithm and preferable precision. Multi-Global Navigation Satellite System (GNSS) is expected to enhance the accuracy, reliability and availability of Differential GNSS (DGNSS) positioning. Traditional DGNSS models should set separate clock parameters due to the clock differences between the different systems. Awareness of the Inter-System Bias (ISB) could help to maximise the redundancy of the positioning model, thus improving the performance of multi-GNSS positioning. This paper aims to examine the inter-system bias of GPS/GLONASS/BeiDou (BDS)/Galileo and their benefits in DGNSS positioning. Results show that Differential ISB (DISB) characteristics vary with different receiver types and systems. The size of DISB could reach metre-level and the precision of estimated DISBs can reach approximately several centimetres within tens of epochs. Therefore, a new real-time DGNSS model that accounts for ISB is proposed. After differential ISBs are initialised, positioning with four satellites from arbitrarily the same or different systems can be realised. Moreover, compared with the traditional DGNSS model, the precision of the positioning results with the new model are obviously improved, especially in harsh environments.

A novel composite was assembled by introducing magnetic Fe 3 O 4 nanoparticles, chitosan and Au nanoparticles (AuNPs) on rectorite (REC) surfaces. The obtained REC-Fe 3 O 4 -CTS-Au composite was characterized and used as the catalyst to remove 4-nitrophenol (4-NP) and methyl orange (MO) from water in the presence of NaBH 4 . The large surface of REC and the abundant hydroxyl group of chitosan on REC surface could restrain the agglomeration of AuNPs. REC-Fe 3 O 4 -CTS-Au exhibited the superiority in catalytic efficiency. At the catalyst dosage of 150 mg/L, it took only 15 min for 0.2 mM 4-NP solution to reach complete reduction, and 30 min for 1.0 mM 4-NP solution. This catalyst had the higher catalytic activity for 4-NP than MO reduction. Moreover, the catalyst could be conveniently separated and recycled from the reaction mixtures using an external magnetic field, and reused for 4-NP (or MO) reduction in fourteen cycles with retaining the original 99% (or 95%) conversion efficiency. This work indicates that REC-Fe 3 O 4 -CTS-Au can be a promising catalyst for the highly efficient degradation of organic dyes.

Differential code bias (DCB) is one of the main error sources of the positioning, navigation and timing services and slant total electron content extraction. The DCB can usually be estimated together with ionospheric model coefficients from the data of International GNSS Service stations. However, the precision of the BeiDou Navigation Satellite System (BDS) satellite DCBs determined with GNSS data is still lower compared with that of GPS. Apart from the sparsely distributed tracking stations of BDS, the quality of BDS observables also matters. Moreover, the determined DCB will have different characteristics for geostationary orbit (GEO), inclined geosynchronous orbit (IGSO) and medium earth orbit (MEO) satellites because of different observation times, geometric structures and orbit repeat periods of the different orbit types. In this study, we mainly analyze the factors affecting the accuracy of BDS satellite DCBs. First, a piece-wise local ionospheric model based on a two-step method is proposed to obtain the BDS DCBs. Second, the impact of BDS satellite-induced code bias variations on the ionospheric observable and DCB determination is analyzed in detail. Finally, we focus on the analysis of the cause of different day-to-day scattering results for GEO, IGSO and MEO satellite DCBs. The performance of the proposed algorithm and the satellite-induced factors affecting the accuracy of BDS DCBs are assessed by about 3 months of GNSS data in 2015 from 42 MGEX stations. Results show that the proposed algorithm is able to estimate BDS satellite DCBs precisely. The DCB day-to-day stability of BDS satellites is improved by 40.6% compared with DCB products of Institute of Geodesy and Geophysics (IGG), China. After the satellite-induced bias is eliminated by a correction model, the precision of BDS DCBs improves. In particular, the value of B1–B3 DCB day-to-day scattering for MEO satellites decreased by 28.4%. In addition, we determined that the lower DCB day-to-day stability of MEO satellites compared with that of IGSO satellites may be mainly attributed to the different satellite orbit repeat periods.

Video summarization aims to provide a compact video representation while preserving the essential activities of the original video. Most existing video summarization approaches relay on identifying important frames and optimizing target energy by a global optimum solution. But global optimum may fail to express continuous action or realistically validate how human beings perceive a story. In this paper, we present a bottom-up approach named clip growing for video summarization, which allows users to customize the quality of the video summaries. The proposed approach firstly uses clustering to oversegment video frames into video clips based on their similarity and proximity. Simultaneously, the importance of frames and clips is evaluated from their corresponding dissimilarity and representativeness. Then, video clips and frames are gradually selected according to their energy rank, until reaching the target length. Experimental results on SumMe dataset show that our algorithm can produce promising results compared to existing algorithms. Several video summarizations results are presented in supplementary material.

Communication networks rely on time synchronization information generated by base station equipment (either the Global Navigation Satellite System receiver or rubidium atomic clock) to enable wireless networking and communications. Meanwhile, the time synchronization among base stations depends on the Network Time Protocol. With the development of mobile communication systems, the corresponding time synchronization accuracy has increased as well. In this case, the use of sparsely distributed-high-precision synchronization points to synchronize time for an entire network with high precision is a key problem and is the foundation of the enhanced network communication. The current receiver equipment for China’s digital synchronous network typically includes dedicated multi-channel GPS receivers for communication; however, with the development of GPS by the USA, network security has been destabilized and reliability is low. Nonetheless, network time synchronization based on Beidou satellite navigation system timing devices is an inevitable development trend for China’s digital communications network with the establishment of the independently developed BDS, especially the implementation and improvement of the Beidou foundation enhancement system.

We report the successful synthesis of a new diluted magnetic semiconductor (Ca,Na)(Zn,Mn)2Sb2. Na and Mn are doped into the parent compound CaZn2Sb2, which has the same crystal structure as that of “122” type iron-based superconductor CaFe2As2. Na substitution for Ca and Mn substitution for Zn introduce carriers and spins, respectively. Doping Mn atoms alone up to 5% does not induce any type of magnetic ordering. When both Na and Mn are co-doped, a ferromagnetic ordering with maximum T C ∼ 10 K has been observed. Iso-thermal magnetization shows that the coercive field is up to ∼ 245 Oe at 2 K. Below T C, a negative magneto-resistance with MR ∼ 12% has also been achieved.

Background: Persistent and intractable hiccups bring serious inconvenience to patients’ work and daily life, and impair their quality of life. Relevant studies showed that acupuncture therapy might be effective in treating persistent and intractable hiccups. However, there is no consistent conclusion so far. The aim of our research is to investigate the safeties and effectiveness of acupuncture in treating patients with persistent and intractable hiccups. Methods: We will search randomized controlled trials (RCTs) using acupuncture therapy to treat persistent and intractable hiccups in the following 6 English electronic databases and 3 Chinese electronic databases: MEDLINE, EMBASE, the Cochrane Library, Web of Science, PsycINFO, Allied and Alternative Medicine (AMED), Chinese National Knowledge Infrastructure (CNKI), Chinese Scientific Journals Database (VIP) and Wanfang data. The cure rate and the total effective rate will be considered as the primary outcomes. Complete cessation within a given period post-treatment of hiccups, changes in frequency or intensity of hiccups, concomitant symptom score, and adverse events will be considered as secondary outcomes. We will use Endnote software 9.1 for studies selection, Review Manager software 5.3, and STATA 13.0 software for analysis and synthesis. Results: we will synthesize current studies to evaluate the the safeties and effectiveness of acupuncture for persistent and intractable hiccups. Conclusion: Our study will provide evidence of acupuncture therapy for persistent and intractable hiccups.

The combined utilization of GPS/BDS has become prevalent to improve the performance of GNSS navigation and positioning. However, the near-static viewing geometry, degraded orbit determination and satellite code bias cause the BDS geostationary (GEO) satellites pseudorange contain more errors and cannot make effectually contribution like other satellites for GPS/BDS combined precise point positioning (PPP), even putting a brake on the convergence. For BDS GEO, the final precise orbit is decimeter level and the satellite-include code bias cannot be modeled effectively. The common method for GEO satellite is to down its weight in GPS/BDS PPP, which causes observations are underutilized. In this paper, we purpose a new method to estimate the unmodelled errors of GEO satellites with all GPS/BDS pseudorange observations. Since all these errors are satellite- dependent, we set separate GEO-offset parameter for each GEO satellite. Coordinates, receiver clock and GEO-offset parameters are estimated together. Many experiments are conducted to present the benefit of the GEO-offset method. At first, we estimate GEO-offset with receiver coordinate unknown or fixed and similar GEO-offset are obtained by two strategies. After corrected by GEO-offsets, most errors can be offset and the variation of corrected multipath observable becomes stable significantly. At last, we apply the GEO-offset into GPS/BDS precise point positioning avoiding a down weight of BDS GEO satellite. The convergence time to the error level of 0.5 m, 0.3 m and 0.15 m are shorted from the average of 16.2 minutes, 23.7 minutes and 51.6 minutes to 5.8 minutes, 11.3 minutes and 20.1 minutes, respectively.

The aim of this work was to study the anticoagulant activity of sulfonated xylan. The crude corncob xylans were isolated from corncob by alkaline extraction. The water-insoluble xylans were sulfonated using chlorosulfonic acid and dimethylformamide (DMF) to generate the water-soluble sulfonated xylan (WISX-S). The best conditions for the esterification were 1:1 of chlorosulfonic acid to DMF, keep time of 6 h and temperature of 70 °C by the orthogonal analysis. Degree of substitution of esterification product was 1.54. Anticoagulant properties of WISX-S1 and WISX-S2 were compared with normal saline and positive control heparin sodium. In vitro tests demonstrated that WISX-S2 can significantly prolong APTT and TT, but not PT. The results suggest that WISX-S2 may play the key role of anticoagulation through the intrinsic pathway and common pathway. The anticoagulant activity of xylan sulfates may be associated with the degree of substitution and molecular weight within a certain range.

In the application of high-precision satellite navigation and positioning, differential GNSS positioning technology is used to eliminate the influence of various errors in order to improve the performance of positioning accuracy. The mathematical physics of differential GNSS positioning technology is based on the same space-time datum (the same orbit and difference parameters). Thus, in the RTCM/RTCA differential protocol, an IOD field is constructed based on the parameters of the GNSS navigation message parameters. The base station transmits the IOD parameter to the rover and compare it with the IOD parameters that formed by rover itself, then it can determine whether they are using the same ephemeris and clock difference parameters. The IOD field in the differential protocol is generally constructed based on a unique parameter in the GNSS navigation message for a certain period of time. There is no special field used to identify the parameter group in the BeiDou navigation message. Therefore, it is necessary to analyze the parameters of the existing navigation message, discuss the mechanism of parameter formation and constrain the broadcasting mechanism of the message so as to solve the obstacles in the scale application of BeiDou high precision differential. In this paper, the technical background of BeiDou RTCM IOD is discussed, the solution is studied and the experimental results show that it is feasible and effective to construct BDS RTCM IOD parameters based on Toe.

It has become a necessary requirement of the time for colleges to carry out enterprise education to produce high-quality personnel with entrepreneur spirit and ability. It is discussed at the beginning of this article that the purpose and status quo of the enterprise education for college students in China and then the reasons for the poor condition in enterprise education are explored. It is found out that colleges do not provide an effective systematic platform for enterprise education; necessary personnel are not provided for such purpose in the teaching staff in Chinese colleges; in actual operation practical effect is not achieved in the moral training in colleges. Therefore, new concept in moral training must be introduced and first-rate teaching staff must be provided for the effective enterprise education. Special courses must also be systematically compiled for the purpose.

As the field of high-precision applications based on carriers continues to expand, the development of low-cost, small, modular receivers and their application in diverse scenarios and situations with complex data quality has increased the requirements of carrier-phase data preprocessing. A new geometry-based cycle slip detection and repair method based on Global Position System (GPS) + BeiDou Navigation Satellite System (BDS) is proposed. The method uses a Time-differenced Carrier Phase (TDCP) model, which eliminates the Inner-System Bias (ISB) between GPS and BDS, and it is conducive to the effective combination of GPS and BDS. It avoids the interference of the noise of the pseudo-range with cycle slip detection, while the cycle slips are preserved as integers. This method does not limit the receiver frequency number, and it is applicable to single-frequency data. The process is divided into two steps to detect and repair cycle slip. The first step is cycle slip detection, using the Improved Local Analysis Method (ILAM) to find satellites that have cycle slips; The second step is to repair the cycle slips, including estimating the float solution of changes in ambiguities at the satellites that have cycle slips with the least squares method and the integer solution of the cycle slips by rounding. In the process of rounding, in addition to the success probability, a decimal test is carried out to validate the result. Finally, experiments with filed test data are carried out to prove the effectiveness of this method. The results show that the detectable cycle slips number with GPS + BDS is much greater than that with GPS. The method can also detect the non-integer outliers while fixing the cycle slip. The maximum decimal bias in repair is less than that with GPS. It implies that this method takes full advantages of multi-system.

Low orbit has features of strong invisibility and penetration, but needs more shutdown energy comparable to high orbit under the same range, which strongly requires studying the problem of delivery capacity optimization for multi-stage launch vehicles. Based on remnant apparent velocity and constraints models, multi-constraint closed-loop guidance with constraints of trajectory maximum height and azimuth was proposed, which adopted elliptical orbit theory and Newton iteration algorithm to optimize trajectory and thrust direction, reached to take full advantage of multi-stage launch vehicle propellant, and guided low orbit vehicle to enter maximum range trajectory. Theory deduction and numerical example demonstrate that the proposed guidance method could extend range and achieve precise control for orbit maximum height and azimuth.