The robot manipulator is commonly employed in the space station experiment cabinet for the disinfection task. The challenge lies in devising a motion trajectory for the robot manipulator that satisfies both performance criteria and constraints within the confined space of an experimental cabinet. To address this issue, this paper proposes a trajectory planning method in joint space. This method constructs the optimal trajectory by transforming the original problem into a constrained multi-objective optimization problem. This is then solved and integrated with the seventh-degree B-spline curve. The optimization algorithm utilizes an indicator-based adaptive differential evolution algorithm, enhanced with improved Tent chaotic mapping and opposition-based learning for population initialization. The method employed the Fréchet distance to design a trajectory selection strategy based on the Pareto solutions to ensure that the planned trajectory complies with Cartesian space requirements. This allows the robot manipulator end-effector to approximate the desired path in Cartesian space closely. The findings indicate that the proposed method can effectively design the robot manipulator trajectory, considering both joint motion performance and end-effector motion constraints. This ensures that the robot manipulator operates efficiently and safely within the experimental cabinet.

While there is evidence that childhood maltreatment (CM) is positively associated with drug use (DU), the strength and difference of the association between CM and its subtypes (hereafter CM + ST) and DU remains to be further explored. A multilevel meta-analysis was conducted on 101 independent studies reporting 333 effect sizes (N = 132,341; Mage = 24.65; 43.80%males). Results showed significantly positive correlations between CM + ST and DU (range from 0.109 to 0.185). The results of the subgroup analysis revealed notable disparities in the correlations between distinct CM subtypes and DU (F = 5.358, P<0.01). Specifically, the effect size for childhood sexual abuse (CSA) was significantly lower than childhood emotional maltreatment (CEM) and childhood physical maltreatment (CPM), while no significant difference was noted between the CEM and CPM groups. These effect sizes also varied across regions, drug types, gender, detection rate of CM, the presence or absence of alcohol in substances, publication status and measurement method. The significant yet differing correlations between different subtypes of CM and DU to some extent support the principle of equality in psychopathology. These findings help explain the relationship between CM + ST and DU laying the groundwork for further research into the intricate and complex associations between CM and DU.

We prove the following restricted projection theorem. Let $n\ge 3$ and $\Sigma \subset S^{n}$ be an $(n-1)$-dimensional $C^2$ manifold such that $\Sigma$ has sectional curvature $\gt1$. Let $Z \subset \mathbb{R}^{n+1}$ be analytic and let $0 \lt s \lt \min\{\dim Z, 1\}$. Then

\begin{equation*} \dim \{z \in \Sigma\; :\; \dim (Z \cdot z) \lt s\} \le (n-2)+s = (n-1) + (s-1) \lt n-1.\end{equation*}

$z \in \Sigma$

$\dim (Z \cdot z) = \min\{\dim Z, 1\}$

The core idea, originated from Käenmäki–Orponen–Venieri, is to transfer the restricted projection problem to the study of the dimension lower bound of Furstenberg sets of cinematic family contained in $C^2([0,1]^{n-1})$. This cinematic family of functions with multivariables are extensions of those of one variable by Pramanik–Yang–Zahl and Sogge. Since the Furstenberg sets of cinematic family contain the affine Furstenberg sets as a special case, the dimension lower bound of Furstenberg sets improves the one by Héra, Héra–Keleti–Máthé and Dąbrowski–Orponen–Villa.

Moreover, our method to show the restricted projection theorem can also give a new proof for the Mattila projection theorem in $\mathbb{R}^n$ with $n \ge 3$.

The recently proposed near-wall turbulence predictive model quantifies the degree of the superposition and the amplitude modulation exerted by large-scale coherent structures on small scales in the linear and nonlinear terms of the formula, respectively, and achieves the prediction of streamwise velocity in the inner region. However, the multiscale effect and the time shift confirmed in the amplitude modulation have not yet been simultaneously taken into account in the model, which could limit the prediction accuracy especially at high Reynolds numbers. In this study, the role of the nonlinear term in the model is clarified based on high-quality flow data obtained in atmospheric surface layers: it redistributes the energy of the universal signal in the time domain and determines the accuracy of the predictive odd moments. An analysis of the multiscale effect and the time shifts in the nonlinear term is subsequently conducted, followed by a demonstration of the refinement in the quality of the universal signal after separately incorporating them into the model. The amplitude modulation is revealed when the two factors are simultaneously considered, and profiles of the scales that dominate the modulation and time shifts with height is provided. Thus, the nonlinear term of the existing model is modified, proposing an polished scheme that can quantify the nonlinear modulation terms more accurately.

We experimentally identify a rotational motion of a single microalga (Chlamydomonas reinhardtii) within a microcontainer believed to be induced by one defective flagellum. We numerically adapt the classic two-dimensional squirmer model to replicate this unique motion by partially inhibiting the slip velocity on the boundaries of the squirmer. Subsequently, we employ a lattice Boltzmann method to simulate the motion of the single microalga with one defective flagellum. We examine the influence of swimming Reynolds numbers, self-propelling strength ($\beta$) and angle ($\alpha$) on the locomotion of the squirmer with one defective flagellum. The results indicate that a large $\beta$ leads to a large rotational diameter, positively correlating with the speed. Additionally, we observe that a low self-propelling strength ($\beta =0.5$) yields a monotonically increasing speed for the squirmer with $\alpha$. In general, high $\beta$ values result in fast speeds for the squirmer. This differs from the behaviour observed in a classic squirmer ($\alpha =360^{\circ }$), where high $\beta$ leads to a slow speed of puller ($\beta \gt 0$) owing to weak fluid inertia effects. Meanwhile, the energy expenditure increases monotonically with $\alpha$, contrasting with the non-monotonic trends observed for swimming speed and rotational diameter.

We present a high-power mid-infrared single-frequency pulsed fiber laser (SFPFL) with a tunable wavelength range from 2712.3 to 2793.2 nm. The single-frequency operation is achieved through a compound cavity design that incorporates a germanium etalon and a diffraction grating, resulting in an exceptionally narrow seed linewidth of approximately 780 kHz. Employing a master oscillator power amplifier configuration, we attain a maximum average output power of 2.6 W at 2789.4 nm, with a pulse repetition rate of 173 kHz, a pulse energy of 15 μJ and a narrow linewidth of approximately 850 kHz. This achievement underscores the potential of the mid-infrared SFPFL system for applications requiring high coherence and high power, such as high-resolution molecular spectroscopy, precision chemical identification and nonlinear frequency conversion.

The attached-eddy model (AEM) predicts that the mean streamwise velocity and streamwise velocity variance profiles follow a logarithmic shape, while the vertical velocity variance remains invariant with height in the overlap region of high Reynolds number wall-bounded turbulent flows. Moreover, the AEM coefficients are presumed to attain asymptotically constant values at very high Reynolds numbers. Here, the AEM predictions are examined using sonic anemometer measurements in the near-neutral atmospheric surface layer, with a focus on the logarithmic behaviour of the streamwise velocity variance. Utilizing an extensive 210-day dataset collected from a 62 m meteorological tower located in the Eastern Snake River Plain, Idaho, USA, the inertial sublayer is first identified by analysing the measured momentum flux and mean velocity profiles. The logarithmic behaviour of the streamwise velocity variance and the associated ‘$-1$’ scaling of the streamwise velocity energy spectra are then investigated. The findings indicate that the Townsend–Perry coefficient ($A_1$) is influenced by mild non-stationarity that manifests itself as a Reynolds number dependence. After excluding non-stationary runs, and requiring the bulk Reynolds number defined using the atmospheric boundary layer height to be larger than $4 \times 10^{7}$, the inferred $A_1$ converges to values ranging between 1 and 1.25, consistent with laboratory experiments. Furthermore, nine benchmark cases selected through a restrictive quality control reveal a close relation between the ‘$-1$’ scaling in the streamwise velocity energy spectrum and the logarithmic behaviour of streamwise velocity variance. However, additional data are required to determine whether the plateau value of the pre-multiplied streamwise velocity energy spectrum is identical to $A_1$.

This study presents a novel investigation into the vortex dynamics of flow around a near-wall rectangular cylinder based on direct numerical simulation at $Re=1000$, marking the first in-depth exploration of these phenomena. By varying aspect ratios ($L/D = 5$, $10$, $15$) and gap ratios ($G/D = 0.1$, $0.3$, $0.9$), the study reveals the vortex dynamics influenced by the near-wall effect, considering the incoming laminar boundary layer flow. Both $L/D$ and $G/D$ significantly influence vortex dynamics, leading to behaviours not observed in previous bluff body flows. As $G/D$ increases, the streamwise scale of the upper leading edge (ULE) recirculation grows, delaying flow reattachment. At smaller $G/D$, lower leading edge (LLE) recirculation is suppressed, with upper Kelvin–Helmholtz vortices merging to form the ULE vortex, followed by instability, differing from conventional flow dynamics. Larger $G/D$ promotes the formation of an LLE shear layer. An intriguing finding at $L/D = 5$ and $G/D = 0.1$ is the backward flow of fluid from the downstream region to the upper side of the cylinder. At $G/D = 0.3$, double-trailing-edge vortices emerge for larger $L/D$, with two distinct flow behaviours associated with two interactions between gap flow and wall recirculation. These interactions lead to different multiple flow separations. For $G/D = 0.9$, the secondary vortex (SV) from the plate wall induces the formation of a tertiary vortex from the lower side of the cylinder. Double-SVs are observed at $L/D = 5$. Frequency locking is observed in most cases, but is suppressed at $L/D = 10$ and $G/D = 0.9$, where competing shedding modes lead to two distinct evolutions of the SV.

In late May 1949, after troops of the Chinese Communist Party (CCP) entered Shanghai, Mansfield Addis, then First Secretary of the British Embassy in Nanjing, wrote to his mother back home: “Shanghai liberated! We rejoice that it was not more difficult! It brings the end nearer.” The sentiment expressed in Addis's letter drew the attention of the British Foreign Office, which felt the matter serious enough to warrant a special telegram to its Nanjing embassy in July 1949:

We notice a growing tendency in telegrams from China to refer to the Communist occupation of an area as “liberation”. In the case of a Consular officer reporting to you en clair and post facto the expression may possibly be unavoidable, but we feel bound to point out that China telegrams get a wide distribution here with the consequent danger that expressions such as this, oft repeated, may serve to strengthen beliefs all too prevalent that Chinese Communism is different from the Soviet brand. We hope therefore that posts will in future refrain from using this word in a sense so far divorced from its true meaning.

An experimental study is conducted to compare droplet generation in a deep-water plunging breaker in filtered tap water and in the presence of low and high bulk concentrations of the soluble surfactant Triton X-100. The breakers are generated by a programmable wave maker that is set with a single motion profile that produces a highly repeatable dispersively focused two-dimensional (2-D) wave packet with a central wavelength of $\lambda _0=1.18\,\rm m$. The droplets are measured with an in-line cinematic holographic system. It is found that the presence of surfactants significantly modifies the overall droplet number and the distributions of droplet diameter and velocity components produced by the four main droplet producing mechanisms of the breaker as identified by Erinin et al. ( J. Fluid Mech., vol. 967, 2023, p. A36). These modifications are due to both surfactant-induced changes in the flow structures that generate droplets and changes in the details of droplet production mechanisms in each flow structure.

Fujian, the coastal province in Southeast China, is where a large number of overseas Chinese called home. After widely publicized tragic events such as the Golden Venture and Dover incidents, the name Fujian has in recent decades become associated with clandestine border entry. This article examines the causes and contexts of undocumented migration from Fujian to Japan. It highlights the unique characteristics of undocumented migration into Japan: debt-driven migration and network-induced visa overstaying. It also explores the tradition- and reciprocity-oriented ethical frameworks within which Fujian undocumented migrants justify their behavior.

In marine and offshore engineering, the presence of air in the water plays a significant role in influencing impact pressures during water entry events. Owing to limited research on the impact loads of aerated water entry, this study aims to explore the effect of aeration on water entry impact pressures. A comprehensive experimental investigation on pure and aerated water entry of a wedge with a 20° deadrise angle was presented. The wire-mesh sensor (WMS) technology was proposed to accurately quantify the spatial and temporal distributions of void fractions in multiphase environments. The WMS provides reliable and consistent measurements at varying void fractions, as validated against image-based methods. The results indicated that the aeration reduced peak impact pressures by up to 33 %, and extended pressure duration, with a linear relationship between impact pressure and void fraction. Furthermore, the probability distribution of peak pressures conformed well to both the generalised extreme value and Weibull distributions, with the void fraction exerting a strong influence on pressure distribution parameters. These findings suggest that controlled aeration can effectively mitigate impact loads, offering practical implications for marine structure design.

This article aims to expand the scope of experimental archaeology to emphasize multilevel variation and interactions across the levels of perception, actions, and outcomes. Such an approach, loosely formulated as the Perception-Process-Product (“Triple P”) framework, offers a more grounded and richer explanation of the past archaeological record. It consists of three principles: (1) acknowledging the inherent trade-off between control and generalizability in the experimental research design; (2) encouraging collaborative projects that involve geographically diverse and nontraditional research participants, such as hobbyists and novices; and (3) adopting a workflow that normalizes the collection and curation of ethological and ethnographic data in experimental projects. Serving as a heuristic device, this alternative mode of knowledge production is highly flexible in nature, where each single component is detachable as dictated by individual research questions.

Understanding the vertical coherence of the pressure structure and its interaction with velocity fields is critical for elucidating the mechanisms of acoustic generation and radiation in hypersonic turbulent boundary layers. This study employs linear coherence analysis to examine the self-similar coherent structures in the velocity and pressure fields within a Mach 6 hypersonic boundary layer, considering a range of wall-to-recovery temperature ratios. The influence of wall cooling on the geometric characteristics of these structures, such as inclination angles and three-dimensional aspect ratios, is evaluated. Specifically, the streamwise velocity exhibits self-similar coherent structures with the streamwise/wall-normal aspect ratio ranging from 16.5 to 38.7, showing a linear increases with decreasing wall temperatures. Similar linear dependence between the streamwise/wall-normal aspect ratio and the wall temperatures are observed for the Helmholtz-decomposed streamwise velocity and the pressure field. In terms of velocity–pressure coupling, the solenoidal component exhibits stronger interactions with the pressure fields in the near-wall region, while the dilatational component has stronger interactions with the pressure field at large scales with the increase of height. Such coupling generally follows the distance-from-the-wall scaling of the pressure field, except in cooled wall cases. Using the linear stochastic estimation, the pressure field across the boundary layer is predicted by inputting the near-wall pressure/velocity signal along with the transfer kernel. The result demonstrates that near-wall pressure signals provide the most accurate description of the pressure field in higher regions of the boundary layer. As wall-mounted sensors can measure near-wall pressure fluctuations, this study presents a potential approach to predict the off-wall pressure field correlated with the near-wall structures based on wall-pressure measurements.

This study investigates the energy exchange between coherent structures in flows over four low-aspect-ratio (low-) plates using the tomographic particle image velocimetry dataset originally obtained by Zhu et al. (2024. J. Fluid Mech. 983, A35). The chord-based Reynolds number is $5400$, with fixed angle of attack $6 ^\circ$. In this study, multiscale proper orthogonal decomposition is applied to extract the coherent structures, including those associated with the vortex-shedding frequency $St_1$ and its subharmonic counterpart. Subsequently, the coherent kinetic energy budget is analysed with a focus on inter-scale energy transfer. This study demonstrates that the energy transfer between the scales centred at $St_1$ and $0.5\,St_1$ can exhibit a reverse or forward direction, depending on the transformation pattern of the leading-edge vortices (LEVs). Specifically, different triadic interactions are excited during the LEV transformation, and manifest themselves during the formation of hairpin vortices downstream. Understanding this nonlinear energy transfer is essential for elucidating mechanisms underlying the development of turbulence in three-dimensional flows over low- plates.