GNSS carrier-phase multipath modeling and correction: a review and prospect of data processing methods

A multipath error is one of the main sources of GNSS positioning errors. It cannot be eliminated by forming double-difference and other methods, and it has become an issue in GNSS positioning error processing, because it is mainly related to the surrounding environment of the station. To address multipath errors, three main mitigation strategies are employed: site selection, hardware enhancements, and data processing. Among these, data processing methods have been a focal point of research due to their cost-effectiveness, impressive performance, and widespread applicability. This paper focuses on the review of data processing mitigation methods for GNSS carrier-phase multipath errors. The paper begins by elucidating the origins and mitigation strategies of multipath errors. Subsequently, it reviews the current research status pertaining to data processing methods using stochastic and functional models to counter multipath errors. The paper also provides an overview of filtering techniques for extracting multipath error models from coordinate sequences or observations. Additionally, it introduces the evolution and algorithmic workflow of sidereal filtering (SF) and multipath hemispherical mapping (MHM), from both coordinate and observation domain perspectives. Furthermore, the paper emphasizes the practical significance and research relevance of multipath error processing. It concludes by delineating future research directions in the realm of multipath error mitigation.</p

BDS dual-frequency carrier phase multipath hemispherical map model and its application in real-time deformation monitoring

The BDS multipath delay error is highly related to the surrounding monitoring environment, which cannot be eliminated or mitigated by applying the double difference observation model. In the actual monitoring environment, due to the complexity of the BDS constellation, it is difficult for existing algorithms to consider GEO, IGSO, MEO and other different orbital types of satellites for real-time and efficient multipath error reduction. Therefore, we propose a novel BDS dual-frequency multipath error reduction method for real deformation monitoring for BDS considering various satellite orbit types. This method extracts the single error residual of each satellite based on the assumption of “zero mean” and divides the appropriate grid density of GEO and IGSO/MEO, respectively, to construct a dual-frequency multipath hemispherical map model suitable for BDS satellites with different orbital types. This method can realize the multipath error elimination of the observed values of different orbits and different frequencies. The results of simulation experiments and real deformation monitoring data demonstrate that this method can effectively eliminate low-frequency multipath delay errors in the observation domain and coordinate domain. After multipath correction, the precision of the horizontal coordinates and height coordinates are 1.7 mm and 4.6 mm. The precision of the horizontal coordinate and height coordinate is increased by 50% and 60%, respectively. The fixed rate of ambiguity increased by 5–7%.</p

Physico-chemical Properties of 1‑Alkyl-3-methylimidazolium Propionate Ionic Liquids {[C_<i>n</i>mim][Pro](<i>n</i> = 3, 4, 5, 6)} from 288.15 K to 328.15 K

Four propionic acid ionic liquids (PrAILs) [C_<i>n</i>mim]­[Pro] (<i>n</i> = 3, 4, 5, 6) (1-alkyl-3-methylimidazolium propionate) were prepared by the neutralization method and characterized by ¹H NMR spectroscopy and differential scanning calorimetry. The values of their density, surface tension, and refractive index were measured in the temperature range of 288.15–328.15 K. Since the PrAILs can strongly form hydrogen bonds with water, the small amount of water is difficult to remove from the PrAILs by conventional methods. To eliminate the effect of the water impurity, the standard addition method (SAM) was applied to these measurements. The dependence of volumetric properties, surface properties, and molar refraction on temperature were discussed. In terms of Kabo’s method the molar enthalpies of vaporization, Δ<i>H</i>^V, for the PrAILs were estimated. As a new idea, it was put forward that Δ<i>H</i>^V can be assumed to consist of two parts: one is the contribution from induced dipole, Δ<i>H</i>^V_<i>n</i>, and the other is the contribution from the permanent dipole of ion pair in ILs, Δ<i>H</i>^V_μ. The values of Δ<i>H</i>^V_<i>n</i> can be estimated in terms of refractive index data so that the values of Δ<i>H</i>^V_μ can be obtained and Δ<i>H</i>^V_μ may be seen as the measure of polarity for ILs

Estimation of Properties of Ionic Liquids 1‑Alkyl-3-methylimidazolium Lactate Using a Semiempirical Method

The ionic liquids based on lactic acid (LAILs)1-ethyl-3-methylimidazolium lactate ([C₂mim]­[Lact]) and 1-pentyl-3-methylimidazolium lactate ([C₅mim]­[Lact])have been prepared by the neutralization method and characterized by ¹H nuclear magnetic resonance (NMR) and differential scanning calorimetry (DSC). The values of their density, surface tension, and refractive index were measured at 298.15 ± 0.05 K. Since the LAILs can form strong hydrogen bonds with water, small amounts of water are difficult to remove via common methods. In order to eliminate the effect of the impurity water, the standard addition method (SAM) was applied to these measurements. An improved semiempirical method to estimate the properties of the ILs has been put forward; that is, in terms of an extrathermodynamic assumption, the values of the individual ion volume, [C₂mim]⁺ and [BF₄]⁻, were successfully evaluated from the molecular volume of the IL [C₂mim]­[BF₄]. Then, using [C₂mim]⁺ as the reference ion, the properties of [Lact]⁻ and [C_<i>n</i>mim]⁺ (<i>n</i> = 3, 4, 5, 6) were calculated from the experimental data of this work. In order to further verify the reliability of this method, the values of the ionic properties for [Ala]⁻, [Pro]⁻, [Gly]⁻, [BF₄]⁻, and [OAc]⁻ were calculated using the same methodology. In terms of the above ionic properties, properties of some ILs, such as molecular volume, parachor, molar refraction were estimated and the estimated values are highly correlated with the corresponding experimental values. At the same time, the parachor estimated by the method above were used to predict the surface tension of the ILs and the predicted values are highly correlated and extremely similar with the corresponding experimental ones. These facts demonstrate the reliability of the improved semiempirical method

Table3_Comprehensive whole-genome resequencing unveils genetic diversity and selective signatures of the Xiangdong black goat.XLSX

Xiangdong black goats, indigenous to Hunan Province, China, exhibit remarkable adaptation to challenging environments and possess distinct black coat coloration alongside exceptional meat quality attributes. Despite their significance, comprehensive genomic investigations of this breed have been notably lacking. This study involved a comprehensive examination of population structure, genomic diversity, and regions of selection in Xiangdong black goats utilizing whole-genome sequencing data from 20 samples of this breed and 139 published samples from six other Chinese goat breeds. Our genomic analysis revealed a total of 19,133,125 biallelic single nucleotide polymorphisms (SNPs) within the Xiangdong black goat genome, primarily located in intergenic and intronic regions. Population structure analysis indicated that, compared with Jintang, Guizhou and Chengdu goats, Xiangdong black goats exhibit a reduced level of genetic differentiation but exhibit relatively greater divergence from Jining goats. An examination of genetic diversity within Xiangdong black goats revealed a moderate level of diversity, minimal inbreeding, and a substantial effective population size, which are more reflective of random mating patterns than other Chinese goat breeds. Additionally, we applied four distinct selective sweep methods, namely, the composite likelihood ratio (CLR), fixation index (FST), θπ ratio and cross-population extended haplotype homozygosity (XP-EHH), to identify genomic regions under positive selection and genes associated with fundamental biological processes. The most prominent candidate genes identified in this study are involved in crucial aspects of goat life, including reproduction (CCSER1, PDGFRB, IFT88, LRP1B, STAG1, and SDCCAG8), immunity (DOCK8, IL1R1, and IL7), lactation and milk production (SPP1, TLL1, and ERBB4), hair growth (CHRM2, SDC1, ITCH, and FGF12), and thermoregulation (PDE10A). In summary, our research contributes valuable insights into the genomic characteristics of the Xiangdong black goat, underscoring its importance and utility in future breeding programs and conservation initiatives within the field of animal breeding and genetics.</p

Table1_Comprehensive whole-genome resequencing unveils genetic diversity and selective signatures of the Xiangdong black goat.XLSX

Xiangdong black goats, indigenous to Hunan Province, China, exhibit remarkable adaptation to challenging environments and possess distinct black coat coloration alongside exceptional meat quality attributes. Despite their significance, comprehensive genomic investigations of this breed have been notably lacking. This study involved a comprehensive examination of population structure, genomic diversity, and regions of selection in Xiangdong black goats utilizing whole-genome sequencing data from 20 samples of this breed and 139 published samples from six other Chinese goat breeds. Our genomic analysis revealed a total of 19,133,125 biallelic single nucleotide polymorphisms (SNPs) within the Xiangdong black goat genome, primarily located in intergenic and intronic regions. Population structure analysis indicated that, compared with Jintang, Guizhou and Chengdu goats, Xiangdong black goats exhibit a reduced level of genetic differentiation but exhibit relatively greater divergence from Jining goats. An examination of genetic diversity within Xiangdong black goats revealed a moderate level of diversity, minimal inbreeding, and a substantial effective population size, which are more reflective of random mating patterns than other Chinese goat breeds. Additionally, we applied four distinct selective sweep methods, namely, the composite likelihood ratio (CLR), fixation index (FST), θπ ratio and cross-population extended haplotype homozygosity (XP-EHH), to identify genomic regions under positive selection and genes associated with fundamental biological processes. The most prominent candidate genes identified in this study are involved in crucial aspects of goat life, including reproduction (CCSER1, PDGFRB, IFT88, LRP1B, STAG1, and SDCCAG8), immunity (DOCK8, IL1R1, and IL7), lactation and milk production (SPP1, TLL1, and ERBB4), hair growth (CHRM2, SDC1, ITCH, and FGF12), and thermoregulation (PDE10A). In summary, our research contributes valuable insights into the genomic characteristics of the Xiangdong black goat, underscoring its importance and utility in future breeding programs and conservation initiatives within the field of animal breeding and genetics.</p

Table2_Comprehensive whole-genome resequencing unveils genetic diversity and selective signatures of the Xiangdong black goat.XLSX

Xiangdong black goats, indigenous to Hunan Province, China, exhibit remarkable adaptation to challenging environments and possess distinct black coat coloration alongside exceptional meat quality attributes. Despite their significance, comprehensive genomic investigations of this breed have been notably lacking. This study involved a comprehensive examination of population structure, genomic diversity, and regions of selection in Xiangdong black goats utilizing whole-genome sequencing data from 20 samples of this breed and 139 published samples from six other Chinese goat breeds. Our genomic analysis revealed a total of 19,133,125 biallelic single nucleotide polymorphisms (SNPs) within the Xiangdong black goat genome, primarily located in intergenic and intronic regions. Population structure analysis indicated that, compared with Jintang, Guizhou and Chengdu goats, Xiangdong black goats exhibit a reduced level of genetic differentiation but exhibit relatively greater divergence from Jining goats. An examination of genetic diversity within Xiangdong black goats revealed a moderate level of diversity, minimal inbreeding, and a substantial effective population size, which are more reflective of random mating patterns than other Chinese goat breeds. Additionally, we applied four distinct selective sweep methods, namely, the composite likelihood ratio (CLR), fixation index (FST), θπ ratio and cross-population extended haplotype homozygosity (XP-EHH), to identify genomic regions under positive selection and genes associated with fundamental biological processes. The most prominent candidate genes identified in this study are involved in crucial aspects of goat life, including reproduction (CCSER1, PDGFRB, IFT88, LRP1B, STAG1, and SDCCAG8), immunity (DOCK8, IL1R1, and IL7), lactation and milk production (SPP1, TLL1, and ERBB4), hair growth (CHRM2, SDC1, ITCH, and FGF12), and thermoregulation (PDE10A). In summary, our research contributes valuable insights into the genomic characteristics of the Xiangdong black goat, underscoring its importance and utility in future breeding programs and conservation initiatives within the field of animal breeding and genetics.</p

Table4_Comprehensive whole-genome resequencing unveils genetic diversity and selective signatures of the Xiangdong black goat.XLSX

Xiangdong black goats, indigenous to Hunan Province, China, exhibit remarkable adaptation to challenging environments and possess distinct black coat coloration alongside exceptional meat quality attributes. Despite their significance, comprehensive genomic investigations of this breed have been notably lacking. This study involved a comprehensive examination of population structure, genomic diversity, and regions of selection in Xiangdong black goats utilizing whole-genome sequencing data from 20 samples of this breed and 139 published samples from six other Chinese goat breeds. Our genomic analysis revealed a total of 19,133,125 biallelic single nucleotide polymorphisms (SNPs) within the Xiangdong black goat genome, primarily located in intergenic and intronic regions. Population structure analysis indicated that, compared with Jintang, Guizhou and Chengdu goats, Xiangdong black goats exhibit a reduced level of genetic differentiation but exhibit relatively greater divergence from Jining goats. An examination of genetic diversity within Xiangdong black goats revealed a moderate level of diversity, minimal inbreeding, and a substantial effective population size, which are more reflective of random mating patterns than other Chinese goat breeds. Additionally, we applied four distinct selective sweep methods, namely, the composite likelihood ratio (CLR), fixation index (FST), θπ ratio and cross-population extended haplotype homozygosity (XP-EHH), to identify genomic regions under positive selection and genes associated with fundamental biological processes. The most prominent candidate genes identified in this study are involved in crucial aspects of goat life, including reproduction (CCSER1, PDGFRB, IFT88, LRP1B, STAG1, and SDCCAG8), immunity (DOCK8, IL1R1, and IL7), lactation and milk production (SPP1, TLL1, and ERBB4), hair growth (CHRM2, SDC1, ITCH, and FGF12), and thermoregulation (PDE10A). In summary, our research contributes valuable insights into the genomic characteristics of the Xiangdong black goat, underscoring its importance and utility in future breeding programs and conservation initiatives within the field of animal breeding and genetics.</p

Superior Li⁺ Kinetics by “Low-Activity-Solvent” Engineering for Stable Lithium Metal Batteries

The structure of solvated Li+ has a significant influence on the electrolyte/electrode interphase (EEI) components and desolvation energy barrier, which are two key factors in determining the Li+ diffusion kinetics in lithium metal batteries. Herein, the “solvent activity” concept is proposed to quantitatively describe the correlation between the electrolyte elements and the structure of solvated Li+. Through fitting the correlation of the electrode potential and solvent concentration, we suggest a “low-activity-solvent” electrolyte (LASE) system for deriving a stable inorganic-rich EEI. Nano LiF particles, as a model, were used to capture free solvent molecules for the formation of a LASE system. This advanced LASE not only exhibits outstanding antidendrite growth behavior but also delivers an impressive performance in Li/LiNi0.8Co0.1Mn0.1O2 cells (a capacity of 169 mAh g–1 after 250 cycles at 0.5 C)