High Precision Hybrid Pulse and Phase-Shift Laser Ranging System

With the rapid development of military, aerospace, and precision manufacturing technology, a multitude of situations need to carry out a large-range and high-precision distance measurement. The growth of measurement applications has led to a higher requirement for the laser ranging technology which can be accomplished by using different patterns. At present, the pulse laser ranging method is widely used for medium-range and long-range measurement because of the fast measurement speed and considerable measurement range. However, the ranging precision is low. The short-distance measurement mostly adopts the phase-shift laser ranging method which has high ranging accuracy but limited measurement range. Therefore, the research on lifting the accuracy of pulse laser ranging method and extending the measurement range of the phase-shift laser ranging method will be carried out. In this thesis, combining the existing pulse laser ranging system and phase-shift laser ranging system, dual-frequency and single-frequency hybrid pulse and phase-shift laser ranging systems are proposed. The basis for solving the current problems of poor measurement precision in pulse laser ranging method and short measurement distance in phase-shift laser ranging method are provided. Also, the designed structures have a broad application prospect in the fields of industrial production, military, and aviation. At the beginning of the thesis, the principle and characteristics of the current typical laser ranging methods are introduced and analyzed. According to the Fourier Series theory, the spectrum analysis of the pulse signal and the relationship between the pulse signal and the same-frequency sinusoidal signal, the idea of phase-shift laser ranging based on pulse modulation signal is generated. Instead of a continuous sinusoidal signal, the laser is modulated with a periodic pulse signal. Distance measurement by calculating the phase difference on the sinusoidal signal extracted from the pulse signal with the same frequency at the receiving end. Based on the principle of conventional dual-frequency phase-shift laser ranging method, a dual-frequency pulse laser ranging method is proposed. The distance to be measured is obtained by transmitting two periodic pulse signals with different frequency and then combining the implementation of rough and accurate measurement outcomes. Afterward, a single-frequency pulse laser ranging method is introduced. After receiving the pulse signal, the direct counter method is used to realize rough measurement and phase-shift of the co-frequency sinusoidal signal is utilized to improve the ranging accuracy. This proposed model has the advantages of high ranging precision and long-distance measurement without any other auxiliary frequency. The accuracy of the phase difference calculation is the most critical element in both the dual-frequency and single-frequency laser ranging systems. Currently, the commonly used phase difference calculation methods operated in phase-shift laser ranging system are digital synchronous detection, fast Fourier transform method, and all phase fast Fourier transform method. Published works have discussed the performance of frequency estimation and initial phase calculation using these approaches. In this thesis, the precision of phase difference measurement based on these methods above is compared. The effects of normalized frequency deviation, white Gaussian noise, harmonics are simulated in MATLAB. Simulation results show that all phase fast Fourier transform method has a superior anti-noise ability so that exceptional accuracy of phase difference measurement can be achieved. Furthermore, as the number of sampling points increases, all phase fast Fourier transform method will obtain a more accurate calculation consequence. Finally, this thesis carries on the co-simulation test of the designed dual-frequency and single-frequency hybrid pulse and phase-shift laser ranging systems in Optisystem and MATLAB. The transmitting frequencies of pulse signals operated in the dual-frequency method are 15 MHz and 150 KHz. The pulse used in the single-frequency method is set to 15 MHz. In the simulation, the performance of proposed methods is tested by setting various measuring distance. When the number of sampling points is 1024, the standard deviation and ranging error of the dual-frequency method are 3.72 cm and 13.6 cm within 963.15 meters. For the single-frequency method, the results show a 3.78 cm standard deviation and 14.6 cm ranging error. Simulation results illustrate that the proposed ranging methods have lower ranging error compared with recently published works. It means that the combination of the pulse method and the phase-shift method can achieve high-accuracy and long-range measurement

Human leukocyte antigen-related susceptibility mechanisms in Hodgkin lymphoma

Classic Hodgkin lymphoma (cHL) is a cancer of the immune system common in adolescents and young adults. The chance to develop cHL is strongly influenced by genetically defined human leukocyte antigen (HLA) types. The main function of HLA is to present antigenic peptides and it is a critical player in the normal immune system. In this thesis we focused on the mechanisms of HLA-related associations with cHL. First, we showed that part of the cHL-associated HLA alleles are associated with loss of HLA expression on tumour cells. Second, we identified novel ERAP – HLA interactions that were specific for cHL patients and not observed in controls. Together these data show that antigen presentation is a critical component in defining the susceptibility to develop cHL. Lastly, we identified an association between cHL and killer cell immunoglobulin-like receptors (KIRs). These KIRs interact with HLA class I molecules expressed on target cells and play an important role in clearance of virus-infected or tumour cells. We found that KIR haplotype B protects against the development of a specific cHL subgroup (EBV+ nodular sclerosis). In addition, we observed presence of KIR2DL2 – HLA-C1 and KIR2DS2 – HLA-C1 at significantly lower carrier frequencies in this cHL subgroup compared to controls. Overall, our studies showed that multiple HLA associated molecules influence susceptibility to develop cHL. The results of this thesis further support the critical role of HLA and antigen presentation in cHL susceptibility and extends on the biological mechanisms underlying the development of cHL

Consistency and Consensus Driven for Hesitant Fuzzy Linguistic Decision Making with Pairwise Comparisons

Hesitant fuzzy linguistic preference relation (HFLPR) is of interest because it provides an efficient way for opinion expression under uncertainty. For enhancing the theory of decision making with HFLPR, the paper introduces an algorithm for group decision making with HFLPRs based on the acceptable consistency and consensus measurements, which involves (1) defining a hesitant fuzzy linguistic geometric consistency index (HFLGCI) and proposing a procedure for consistency checking and inconsistency improving for HFLPR; (2) measuring the group consensus based on the similarity between the original individual HFLPRs and the overall perfect HFLPR, then establishing a procedure for consensus ensuring including the determination of decision-makers weights. The convergence and monotonicity of the proposed two procedures have been proved. Some experiments are furtherly performed to investigate the critical values of the defined HFLGCI, and comparative analyses are conducted to show the effectiveness of the proposed algorithm. A case concerning the performance evaluation of venture capital guiding funds is given to illustrate the availability of the proposed algorithm. As an application of our work, an online decision-making portal is finally provided for decision-makers to utilize the proposed algorithms to solve decision-making problems.Comment: Pulished by Expert Systems with Applications (ISSN: 0957-4174

Application of Eh-pH Diagrams on Acid Leaching Systems for the Recovery of REEs from Bastnaesite, Monazite and Xenotime

Bastnaesite, monazite and xenotime are rare earth minerals (REMs) that are typical sources for rare earth elements (REEs). To advance the understanding of their leaching and precipitation behavior in different hydrometallurgical processes, Eh-pH diagrams were constructed and modified using the HSC 9.9 software. The aqueous stability of rare earth elements in H2O and acid leaching systems, i.e., the REE-Ligands-H2O systems, were depicted and studied based on the Eh-pH diagrams. This study considers the most relevant lixiviants, their resulting equilibrium states and the importance in the hydrometallurgical recovery of rare earth elements (REMs). A literature review was performed summarizing relevant Eh-pH diagrams and associated thermodynamic data. Shifting stability regions for REEs were discovered with additions of acid ligands and a narrow stability region for soluble REE-(SO4/Cl/NO3) complexes under highly acidic conditions. As such, the recovery of REEs can be enhanced by adjusting pH and Eh values. In addition, the Eh-pH diagrams of the major contaminants (i.e., Fe, Ca and Al) in leaching systems were studied. The resulting Eh-pH diagrams provide possible insights into potential passivation on the particle surfaces due to the formation of an insoluble product layer

Heterogeneous group decision making with thermodynamical parameters

There often exist different types of information due to the subjective and objective criteria in practical decision-making problems, thus it is necessary to develop some efficient frameworks to deal with the decision-making problems with heterogeneous information. The paper proposes a framework for group decisionmaking problems with heterogeneous information with thermodynamical parameters consisting of three parts to achieving this goal. The first part builds the rectifications of criteria weights according to decision makers’ confidence in evaluations. The second part adopts thermodynamical parameters to measure the numerical values and the data distribution of heterogeneous information to characterize the heterogeneous information fully. The last part applies the TODIM (an acronym in Portuguese for Interactive and Multicriteria Decision Making) to aggregate the decision-making results based on the characterized heterogeneous information without transforming it into a unified form. By depicting decision makers’ different sensitive attitudes towards uncertainty by several mathematical expressions, experiments are performed to assess the sensitive attitudes’ impacts on decisionmaking results with the proposed framework. Finally, a case study on the selection of a green supplier under the low-carbon economy is provided to illustrate the flexibility and feasibility of the proposed framework