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The current sugarcane seeding mechanism is unable to accomplish complex seeding movement trajectories and postures, thus failing to enable the cane seed to enter the seed trench in a stable posture, resulting in a high rate of collapse and a low survival rate. A second-order non-circular planetary gear system pendulum-type seeding mechanism is adopted to realize the complex motion of seeding arm taking seeds in an orderly manner, transporting seeds stably, and sowing seeds in a fixed posture. Constraining the position and posture of the end point of the seeding arm, based on the principle of second-order center distance invariance in the motion process of the planetary gear train, the inverse optimization design model of approximate multi-positional posture is established, and the initial optimal parameters of the double-motion point of the mechanism are solved by genetic algorithm. The second-order non-circular gear ratios are assigned according to the kinematic characteristics of the mechanism in order to design all the non-circular gear pitch curves and model their convexity calculations. In order to avoid the influence on the preset position and posture, the position of the corresponding relative angular displacement fitting point of the adjustable trajectory segment on the closed motion trajectory is taken as the optimization variable, and the convexity optimization model of the second-order non-circular gear pitch curve is established. A set of non-circular gear pitch curves with better roundness is obtained by NSGA II multi-objective optimization algorithm combined with entropy weight TOPSIS game theory. The simulation results show that the motion trajectory posture of the virtual prototype is basically consistent with the theoretical model, which meets the agronomic requirements of sugarcane seeding and verifies the feasibility of the mechanism design.

Nicolaus Copernicus's problematic involved several major areas of concern—planetary modeling, the ordering of the planets, the consequences of such ordering for natural philosophy, and the prediction of future configurations of the heavens and their influences. Unlike theologically motivated fourteenth-century flirtations with the possibility of the Earth's daily rotation, Copernicus's revision of the planetary order occurred at a juncture with the emergent fifteenth-century cultures of print and prognostication: the mobilization of print in the service of both the theoretical and the practical literature of forecast, the creation of new conditions of prognosticatory authorship, the appropriation of resources of humanist rhetoric and dialectic, and the upsurge in apocalyptic expectation. This chapter discusses the Copernican question, prognostication in astrology and revolution in astronomy, world systems and comparative probability, the emergence of natural philosophy, the via moderna versus the via media at the point of mid-century, the Copernican question after the mid-century, and the works of Robert Hooke and Isaac Newton.

Attention to the science of astronomy, already so well sustained in the Wittenberg cultural sphere, received an unexpected boost with the dramatic and unheralded arrival of two apparitions in the skies of the 1570s. One of these was a brilliant entity—represented variously as a meteor, a comet, or a new star—that appeared in 1572 and remained until May 1574; the other—represented almost universally as a “bearded star” or comet—could be seen for just over two months between November 1577 and January 1578. These unforeseen appearances, taken to be evidence of God’s extraordinary capacity to intervene in

SignificanceThis work presents experimental evidence for the formation of a phase with eightfold coordination of germanium by oxygen in Mg2GeO4, a well-known analogue of Mg2SiO4 at extreme pressure and temperatures. Using both experiments and theoretical computations, we have determined the structure, equation of state, and phase stability of this phase at pressures above 200 GPa. The existence of this phase in the silicate counterpart may play an important role in the structure and dynamics of the deep interiors of large, rocky exoplanets. Mg2GeO4 is important as an analog for the ultrahigh-pressure behavior of Mg2SiO4, a major component of planetary interiors. In this study, we have investigated magnesium germanate to 275 GPa and over 2,000 K using a laser-heated diamond anvil cell combined with in situ synchrotron X-ray diffraction and density functional theory (DFT) computations. The experimental results are consistent with the formation of a phase with disordered Mg and Ge, in which germanium adopts eightfold coordination with oxygen: the cubic, Th3P4-type structure. DFT computations suggest partial Mg-Ge order, resulting in a tetragonal I4¯2d structure indistinguishable from I4¯3d Th3P4 in our experiments. If applicable to silicates, the formation of this highly coordinated and intrinsically disordered phase may have important implications for the interior mineralogy of large, rocky extrasolar planets.

Near-shore marine sediments deposited during the Paleocene–Eocene Thermal Maximum at Wilson Lake, NJ, contain abundant conventional and giant magnetofossils. We find that giant, needle-shaped magnetofossils from Wilson Lake produce distinct magnetic signatures in low-noise, high-resolution first-order reversal curve (FORC) measurements. These magnetic measurements on bulk sediment samples identify the presence of giant, needle-shaped magnetofossils. Our results are supported by micromagnetic simulations of giant needle morphologies measured from transmission electron micrographs of magnetic extracts from Wilson Lake sediments. These simulations underscore the single-domain characteristics and the large magnetic coercivity associated with the extreme crystal elongation of giant needles. Giant magnetofossils have so far only been identified in sediments deposited during global hyperthermal events and therefore may serve as magnetic biomarkers of environmental disturbances. Our results show that FORC measurements are a nondestructive method for identifying giant magnetofossil assemblages in bulk sediments, which will help test their ecology and significance with respect to environmental change.

Urban studies today is marked by many active debates. In an earlier paper, we addressed some of these debates by proposing a foundational concept of urbanisation and urban form as a way of identifying a common language for urban research. In the present paper we provide a brief recapitulation of that framework. We then use this preliminary material as background to a critique of three currently influential versions of urban analysis, namely, postcolonial urban theory, assemblage theoretic approaches and planetary urbanism. We evaluate each of these versions in turn and find them seriously wanting as statements about urban realities. We criticise (a) postcolonial urban theory for its particularism and its insistence on the provincialisation of knowledge, (b) assemblage theoretic approaches for their indeterminacy and eclecticism and (c) planetary urbanism for its radical devaluation of the forces of agglomeration and nodality in urban-economic geography.

Thermal tides are atmospheric planetary‐scale waves with periods that are harmonics of the solar day. In the Martian atmosphere thermal tides are known to be especially significant compared to any other known planet. Based on the data set of pressure timeseries produced by the InSight lander, which is unprecedented in terms of accuracy and temporal coverage, we investigate thermal tides on Mars and we find harmonics even beyond the number 24, which exceeds significantly the number of harmonics previously reported by other works. We explore comparatively the characteristics and seasonal evolution of tidal harmonics and find that even and odd harmonics exhibit some clearly differentiated trends that evolve seasonally and respond to dust events. High‐order tidal harmonics with small amplitudes could transiently interfere constructively to produce meteorologically relevant patterns. Plain Language Summary In analogy to the string of a guitar, which can oscillate in integer harmonics, planetary atmospheres exhibit oscillations that are harmonics of the solar day (Harmonic 1 with a period of 24 hr; harmonic 2, 12 hr; harmonic 3, 8 hr; etc.). These oscillations are part of the so‐called “atmospheric thermal tides”, which retain a complex global structure. They are conceptually related to ocean gravitational tides, and they have been observed in atmospheres of the solar system whose main source of energy is the light from the sun: Earth, Mars, Venus, and Titan. On Mars, thermal tides are particularly strong and they play a key role in atmospheric dynamics, presenting interactions with meteorological phenomena such as dust storms. Most studies on thermal tides focus on low‐order harmonics (1, 2, 3, and sometimes 4). In this study, we use a particularly sensitive pressure sensor that landed on Mars with the InSight mission to explore the existence of high‐order harmonics, and we find clear harmonics with very small amplitudes even beyond harmonic 24, which corresponds to 24 oscillations per solar day. We compare the characteristics of those harmonics and analyze their seasonal behavior, and we find that even and odd harmonics exhibit clearly different behaviors. Key Points Analysis of an unprecedented data set of pressure obtained by InSight suggests that tidal harmonics beyond 24 are present on Mars Even and odd modes exhibit distinct patterns with a seasonal dependency centered on equinoxes and solstices, and response to dust events

The high-pressure melting curve of FeO controls key aspects of Earth’s deep interior and the evolution of rocky planets more broadly. However, existing melting studies on wüstite were conducted across a limited pressure range and exhibit substantial disagreement. Here we use an in-situ dual-technique approach that combines a suite of >1000 x-ray diffraction and synchrotron Mössbauer measurements to report the melting curve for Fe 1- x O wüstite to pressures of Earth’s lowermost mantle. We further observe features in the data suggesting an order-disorder transition in the iron defect structure several hundred kelvin below melting. This solid-solid transition, suggested by decades of ambient pressure research, is detected across the full pressure range of the study (30 to 140 GPa). At 136 GPa, our results constrain a relatively high melting temperature of 4140 ± 110 K, which falls above recent temperature estimates for Earth’s present-day core-mantle boundary and supports the viability of solid FeO-rich structures at the roots of mantle plumes. The coincidence of the defect order-disorder transition with pressure-temperature conditions of Earth’s mantle base raises broad questions about its possible influence on key physical properties of the region, including rheology and conductivity. Multi-technique synchrotron measurements support the viability of solid FeO-rich structures at Earth’s mantle base. An order-disorder transition identified in the iron defect structure of FeO may lead to unique physical properties in the region.

As one of the most vital energy conversation systems, the safe operation of wind turbines is very important; however, weak fault and time-varying speed may challenge the conventional monitoring strategies. Thus, an entropy-aided meshing-order modulation method is proposed for detecting the optimal frequency band, which contains the weak fault-related information. Specifically, the variable rotational frequency trend is first identified and extracted based on the time–frequency representation of the raw signal by constructing a novel scaling-basis local reassigning chirplet transform (SLRCT). A new entropy-aided meshing-order modulation (EMOM) indicator is then constructed to locate the most sensitive modulation frequency area according to the extracted fine speed trend with the help of order tracking technique. Finally, the raw vibration signal is bandpass filtered via the corresponding optimal frequency band with the highest EMOM indicator. The order components resulting from the weak fault can be highlighted to accomplish weak fault detection. The effectiveness of the proposed EMOM analysis-based method has been tested using the experimental data of three different gear fault types of different fault levels from a planetary test rig.

The vibration signal of the planetary gear train is easily disturbed by the background noise, so the measured signal is complicated. In order to accurately extract the fault features, the resonance method has been widely used. However, even if the optimal resonance frequency band is found, the in-band noise still exists, so it is necessary to study an effective in-band denoising method. In this paper, an in-band denoising method based on Iterative Singular Value Decomposition (ISVD) is proposed for the fault diagnosis of the secondary sun gear of a planetary gear train, combined with the envelope order spectrum analysis. This method uses the enhanced Wavelet Packet Transform Spectral Kurtosis (WPTSK) to determine the best frequency band for the signal, and uses the ISVD method to realize the signal denoising. It sets a threshold to avoid the destruction of the useful information caused by the excessive iteration, and uses the relationship between the singular values and frequency components to reconstruct the denoised signal. Finally, the signal is converted to the fault characteristic order domain by resampling to identify the fault type of the sun gear from the envelope order spectrum. The simulation and experimental results show that compared with the Empirical Mode Decomposition (EMD) and Variational Mode Decomposition (VMD), the ISVD can effectively suppress the in-band noise and more accurately extract the fault characteristic order of the secondary sun gear under varying speed.