In this paper, a general method for synthesizing dispersive coupling matrix (DCM) of coupled-resonator bandpass filters with the general dispersion is proposed. Compared to the dispersion-less coupling matrix synthesized by classic approaches, the DCM incorporates the identity of the physical realization and provides an accurate description of the filter. Moreover, the DCM can accurately describe the complex resonators and coupling elements with intentional strong dispersion. A DCM consists of two parts: the frequency-invariant part that corresponds to the coupling matrix at the center frequency and the frequency-variant part that reflects the dispersion of the physical realization. By iteratively adjusting the transmission zeros governed by the given filter topology and ignoring the transmission zeros brought by the dispersion, the synthesis method can directly obtain the frequency-invariant part so that the overall DCM leads to an equal-ripple response. To illustrate the general synthesis method, two design examples are presented, which include a filter with unintentional weak dispersion and a filter with intentional strong dispersion. The examples are validated by EM simulation, demonstrating the effectiveness, accuracy, and generality of the proposed synthesis framework. Key words: dispersive coupling matrix, filter synthesis, microwave bandpass filter

We construct an example of a Hamiltonian flow $f^t$ on a four-dimensional smooth manifold $\mathcal {M}$ which after being restricted to an energy surface $\mathcal {M}_e$ demonstrates essential coexistence of regular and chaotic dynamics, that is, there is an open and dense $f^t$-invariant subset $U\subset \mathcal {M}_e$ such that the restriction $f^t|U$ has non-zero Lyapunov exponents in all directions (except for the direction of the flow) and is a Bernoulli flow while, on the boundary $\partial U$, which has positive volume, all Lyapunov exponents of the system are zero.

A deep ice core was drilled at Dome A, Antarctic Plateau, East Antarctica, which started with the installation of a casing in January 2012 and reached 800.8 m in January 2017. To date, a total of 337 successful ice-core drilling runs have been conducted, including 118 runs to drill the pilot hole. The total drilling time was 52 days, of which eight days were required for drilling down and reaming the pilot hole, and 44 days for deep ice coring. The average penetration depths of individual runs were 1 and 3.1 m for the pilot hole drilling and deep ice coring, respectively. The quality of the ice cores was imperfect in the brittle zone (650−800 m). Some of the troubles encountered are discussed for reference, such as armoured cable knotting, screws falling into the hole bottom, and damaged parts, among others.

We consider the situation of a misalignment between the global temperature gradient and gravity in thermal convection. In such a case an effective horizontal buoyancy arises that will significantly influence the transport properties of heat, mass and momentum. It may also change the flow morphology in turbulent convection. In this paper, we present an experimental and numerical study, using Rayleigh–Bénard convection as a platform, to explore systematically the effect of horizontal buoyancy on heat transport in turbulent thermal convection. Experimentally, a condition of increasing horizontal Rayleigh number ($Ra_H$, which is the non-dimensional horizontal thermal driving strength) under fixed vertical Rayleigh number ($Ra_V$, the non-dimensional vertical driving strength) is achieved by tilting the convection cell and simultaneously increasing the imposed temperature difference. We find that, with increasing horizontal to vertical buoyancy ratio ($\varLambda = Ra_H/Ra_V$), the overall heat transport manifests a monotonic increase in vertical heat transport ($Nu_V$) as well as a monotonic increase in its horizontal component ($Nu_H$). However, the horizontal Nusselt number is found to be approximately one order of magnitude smaller than the vertical Nusselt for the parameter range explored. We also show that the non-zero $Nu_H$ results from the broken azimuthal symmetry of the system induced by the horizontal buoyancy. We find that the enhancement of vertical heat transport comes from the increased shear generated by the horizontal buoyancy at the boundary layer. The effect of Prandtl number ($Pr$) is also studied numerically. Finally, we extend the Grossmann–Lohse theory to the case with an effective horizontal buoyancy, the result of which is successful in predicting $Nu_V(Ra_V,\varLambda ,Pr)$.

The soft actuator is made of superelastic material and embedded flexible material. In this paper, a kind of soft tube was designed and used to assemble two kinds of pneumatic soft actuators. The experiment and finite element analysis are used to comprehensively analyze and describe the bending, elongation, and torsion deformation of the soft actuator. The results show that the two soft actuators have the best actuation performance when the inner diameter of the soft tube is 4 mm. In addition, when the twisting pitch of the torsional actuator is 24 mm, its torsional performance is optimized. Finally, a device that can be used in the production line was assembled by utilizing those soft actuators, and some operation tasks were completed. This experiment provides some insights for the development of soft actuators with more complex motions in the future.

Cable is the most important bearing structure of the cable-stayed bridges. Its safety has been of crucial public concern. Traditional manual cable inspection method has many defects such as low inspection efficiency, poor reliability and hazardous working environment. In this paper, a new wirelessly controlled cable-climbing robot enabling safe and convenient inspection of stay cables is proposed. The designed robot is composed of two modules, joined by four turnbuckles to form a closed structure that clasps the cable. The robot is controlled wirelessly by a ground-based station, and a DC power is supplied via an onboard lithium battery. The climbing principle and mechanical structure of this robot are introduced. The static model of the robot during obstacle negotiation is established. The relationships of the driving force and resistance with obstacle height to determine the obstacle-negotiation capability of the robot are obtained. The effects of cable diameter, cable inclination and preload force on obstacle climbing ability of the robot are also analyzed. The experiments verify that the robot could climb random inclined cables and overcome an obstacle of 2.42 mm in height with a mass of 5 kg payload.

With the rapid rise in the prevalence of non-tuberculous mycobacteria (NTM) diseases across the world, the microbiological diagnosis of NTM isolates is becoming increasingly important for the diagnosis and treatment of NTM disease. In this study, the clinical presentation, species distribution and drug susceptibility of patients with NTM disease visiting the Chongqing Public Health Medical Centre during March 2016–April 2019 were retrospectively analysed. Among the 146 patients with NTM disease, eight NTM species (complex) were identified. The predominant NTM species in these patients were identified to be Mycobacterium abscessus complex (53, 36.3%), M. intracellulare (38, 26%) and M. fortuitum (17, 11.7%). In addition, two or more species were isolated from 7.5% of the patients. Pulmonary NTM disease (142, 97.3%) showed the highest prevalence among the patients. It was observed that 40.1% of the patients with pulmonary NTM disease had chronic pulmonary obstructive disease and bronchiectasis, while 22.5% had prior tuberculosis. Male patients showed more association with the conditions of cough and haemoptysis than the female patients. In an in vitro antimicrobial susceptibility testing, most of the species showed susceptibility to linezolid, amikacin and clarithromycin, while M. fortuitum exhibited low susceptibility to tobramycin. In conclusion, the prevalence of NTM disease, especially that of the pulmonary NTM disease, is common in Southwest China. Species identification and drug susceptibility testing are thus extremely important to ensure appropriate treatment regimens for patient care and management.

The epidemic of coronavirus disease 2019 (COVID-19) began in China and had spread rapidly to many other countries. This study aimed to identify risk factors associated with delayed negative conversion of SARS-CoV-2 in COVID-19 patients. In this retrospective single-centre study, we included 169 consecutive patients with confirmed COVID-19 in Zhongnan Hospital of Wuhan University from 15th January to 2nd March. The cases were divided into two groups according to the median time of SARS-CoV-2 negative conversion. The differences between groups were compared. In total, 169 patients had a median virus negative conversion time of 18 days (interquartile range: 11–25) from symptom onset. Compared with the patients with short-term negative conversion, those with long-term conversion had an older age, higher incidence of comorbidities, chief complaints of cough and chest distress/breath shortness and severer illness on admission, higher level of leucocytes, neutrophils, aspartate aminotransferase, creatine kinase and erythrocyte sedimentation rate (ESR), lower level of CD3+CD4+ lymphocytes and albumin and more likely to receive mechanical ventilation. In multivariate analysis, cough, leucocytes, neutrophils and ESR were positively correlated with delayed virus negative conversion, and CD3+CD4+ lymphocytes were negatively correlated. The integrated indicator of leucocytes, neutrophils and CD3+CD4+ lymphocytes showed a good performance in predicting the negative conversion within 2 weeks (area under ROC curve (AUC) = 0.815), 3 weeks (AUC = 0.804), 4 weeks (AUC = 0.812) and 5 weeks (AUC = 0.786). In conclusion, longer quarantine periods might be more justified for COVID-19 patients with cough, higher levels of leucocytes, neutrophils and ESR and lower levels of CD3+CD4+ lymphocytes.

High-entropy alloys (HEAs) are proposed as potential structural materials for advanced nuclear systems, but little is known about the response of matrix chemistry in HEAs upon irradiation. Here, we reveal a substantial change of matrix chemical concentration as a function of irradiation damage (depth) in equiatomic NiCoFeCr HEA irradiated by 3 MeV Ni ions. After ion irradiation, the matrix contains more Fe/Cr in depth shallower than ~900–1000 nm but more Ni/Co from ~900–1000 nm to the end of the ion-damaged region due to the preferential diffusion of vacancies through Fe/Cr. Preferential diffusion also facilitates migration of vacancies from high radiation damage region to low radiation damage region, leading to no void formation below ~900–1000 nm and void formation around the end of the ion-damaged region at a fluence of 5 × 1016 cm−2 (~123 dpa, displacements per atom, peak dose under full cascade mode). As voids grow significantly at an increased fluence (8 × 1016 cm−2, 196 dpa), the matrix concentration does not change dramatically due to new voids formed below ~900–1000 nm.

The dynamical stability of the cable-driven lower-limb rehabilitation training robot (CLLRTR) is a crucial question. Based on the established dynamics model of CLLRTR, the solution to the wrench closure of the under-constrained system is presented. Secondly, the stability index of CLLRTR is proposed by the Krasovski method. Finally, in order to analyze the stability distribution of CLLRTR in the workspace, the stability evaluation index in the workspace is calculated using the eigenvalue decomposition method. The stability distribution laws of CLLRTR are further verified by the experimental study. The results provide references for studying trajectory planning and anti-pendulum control of CLLRTR.

The search space of the path planning problem can greatly affect the running time and memory consumption, for example, the concave obstacle in grid-based map usually leads to the invalid search space. In this paper, the filling container algorithm is proposed to alleviate the concave area problem in 2D map space, which is inspired from the scenario of pouring water into a cup. With this method, concave areas can be largely excluded by scanning the map repeatedly. And the effectiveness has been proved in our experiments.

Increased intake of vegetables and fruits has been associated with reduced risk of tuberculosis infection. Vegetables and fruits exert immunoregulatory effects; however, it is not clear whether vegetables and fruits have an adjuvant treatment effect on tuberculosis. Between 2009 and 2013, a hospital-based cohort study was conducted in Linyi, Shandong Province, China. Treatment outcome was ascertained by sputum smear and chest computerised tomography, and dietary intake was assessed by a semi-quantitative FFQ. The dietary questionnaire was conducted at the end of month 2 of treatment initiation. Participants recalled their dietary intake of the previous 2 months. A total of 2309 patients were enrolled in this study. After 6 months of treatment, 2099 patients were successfully treated and 210 were uncured. In multivariate models, higher intake of total vegetables and fruits (OR 0·70; 95 % CI 0·49, 0·99), total vegetables (OR 0·68; 95 % CI 0·48, 0·97), dark-coloured vegetables (OR 0·61; 95 % CI 0·43, 0·86) and light-coloured vegetables (OR 0·67; 95 % CI 0·48, 0·95) were associated with reduced failure rate of tuberculosis treatment. No association was found between total fruit intake and reduced failure rate of tuberculosis treatment (OR 0·98; 95 % CI 0·70, 1·37). High intake of total vegetables and fruits, especially vegetables, is associated with lower risk of failure of tuberculosis treatment in pulmonary tuberculosis patients. The results provide important information for dietary guidelines during tuberculosis treatment.

A one-dimensional steady-state model for stimulated Raman backscatter (SRS) and stimulated Brillouin backscatter (SBS) processes in laser-irradiated plasmas is presented. Based on a novel “predictor-corrector” method, the model is capable to deal with broadband scattered light and inhomogeneous plasmas, exhibiting robustness and high efficiency. Influences of the electron density and temperature on the linear gains of both SRS and SBS are investigated, which indicates that the SRS gain is more sensitive to the electron density and temperature than that of the SBS. For the low-density case, the SBS dominates the scattering process, while the SRS exhibits much higher reflectivity in the high-density case. The nonlinear saturation mechanisms and competition between SRS and SBS are included in our model by a phenomenological method. The typical anti-correlation between SRS and SBS versus electron density is reproduced in the model. Calculations of the reflectivities are qualitatively in agreement with the typical results of experiments and simulations.

In this work, two types of zinc adipate β-nucleating agents, Adi-Zn(OH)2 (1:1) and Adi-ZnO (1:1), for polypropylene (PP) were prepared and their performances were evaluated and compared with commercial β-nucleating agent (named CNA). Results showed that Adi-Zn(OH)2 (1:1) was more effective in promoting PP to form β-crystals and improving the impact strength of PP in the range of nucleating agent addition (0–0.4 wt%). Based on these findings, the ratio of adipic acid to zinc hydroxide and the nonisothermal crystallization kinetics of the optimum ratio of adipic acid to zinc hydroxide were systematically studied; results showed that at 0.2 wt%, Adi-Zn(OH)2 (1:2), the nucleated PP displayed the highest impact strength, which was 2.6 times that of pure PP and 42% higher than that of CNA. Besides, Adi-Zn(OH)2 (1:2) could also afford to induce the formation of a high content of β-crystals and shorten the crystallization half time (t1/2) and accelerate the crystallization of PP.

Severe phase coarsening and separation in Sn–Bi alloys have brought increasing reliability concern in microelectronic packages. In this study, a phase field model is developed to simulate the microstructural evolution and evaluate the change in macroscopic physical properties of the flip chip Cu/Sn58Bi/Cu joint under the conditions of isothermal aging, as well as the coupled loads of elastic stress and electric current stressing. Results show that large-sized Bi-rich phase particles grow up at the expense of small-sized ones. Under the coupled loads, Bi atoms migrate along the electron flow direction, consequently Bi-rich phase segregates to form a Bi-rich phase layer at the anode. The current crowding ratio in the solder decreases rapidly first and then fluctuates slightly with time. Current density and von Mises stress exhibit inhomogeneous distribution, and both of them are higher in the Sn-rich phase than in the Bi-rich phase. Electric current transfers through the Sn-rich phase and detours the Bi-rich phase. As time proceeds, the resistance of the solder joint increases, and the average von Mises stress of the solder joint decreases. The Bi-rich phase coarsens much faster under the coupled loads than under the conditions of isothermal aging.

We present an experimental and numerical study of natural convection with moist air as convecting fluid. By simplifying the system as two-component convection, an experimental method is proposed for indirectly measuring the moisture transfer rates in buoyancy-driven flows. We verify the results using direct numerical simulations. It is found that the non-dimensionalized transfer rates for both sensible heat ($Nu_{T}$) and water vapour ($Nu_{e}$) are essentially determined by a generalized Grashof number $Gr$ (the ratio of combined buoyancy generated by the imposed temperature and vapour pressure gradients to viscous force), and are only weakly dependent on the buoyancy ratio $\unicode[STIX]{x1D6EC}$ (the ratio of buoyancy induced by temperature variation to that due to vapour pressure variation). Moreover, we show that the full set of control parameters $\{Gr,\unicode[STIX]{x1D6EC},Pr,Sc\}$ is more suitable than other choices for characterizing the two-component system under investigation. As a special case, the Schmidt number dependence for passive scalar transport rates in buoyancy-driven flows is also deduced.