A 3-Node Co-Rotational Triangular Finite Element for Non-Smooth,Folded and Multi-Shell Laminated Composite Structures

Based on the first-order shear deformation theory,a 3-node co-rotational triangular finite element formulation is developed for large deformation modeling of non-smooth,folded and multi-shell laminated composite structures.The two smaller components of the mid-surface normal vector of shell at a node are defined as nodal rotational variables in the co-rotational local coordinate system.In the global coordinate system,two smaller components of one vector,together with the smallest or second smallest component of another vector,of an orthogonal triad at a node on a non-smooth intersection of plates and/or shells are defined as rotational variables,whereas the two smaller components of the mid-surface normal vector at a node on the smooth part of the plate or shell(away from non-smooth intersections)are defined as rotational variables.All these vectorial rotational variables can be updated in an additive manner during an incremental solution procedure,and thus improve the computational efficiency in the nonlinear solution of these composite shell structures.Due to the commutativity of all nodal variables in calculating of the second derivatives of the local nodal variables with respect to global nodal variables,and the second derivatives of the strain energy functional with respect to local nodal variables,symmetric tangent stiffness matrices in local and global coordinate systems are obtained.To overcome shear locking,the assumed transverse shear strains obtained from the line-integration approach are employed.The reliability and computational accuracy of the present 3-node triangular shell finite element are verified through modeling two patch tests,several smooth and non-smooth laminated composite shells undergoing large displacements and large rotations.

The Shizikou Gravitational Gliding Structure in the Three Gorges of the Yangtze River

A study has been made about the structural attribute of the NNW-trendingShizikou linear image belt in the head area of the reservoir of the Yangtze River Gorges and theevaluation of its crustal stability. On the basis of regional geological surveys and by making astructural analysis and a multidisciplinary study, it has been ascertained that the segment withthe best displayed image characteristics is marked by a gravity gliding structure with a multilay-er gliding fold type architecture. This paper also analyzes the medium conditions, slope struc-ture and dynamic setting for the formation of the structure system.

Folding beam-type piezoelectric phononic crystal with low-frequency and broad band gap

A folding beam-type piezoelectric phononic crystal model is proposed to isolate vibration. Two piezoelectric bimorphs are joined by two masses as a folding structure to comprise each unit cell of the piezoelectric phononic crystal. Each bimorph is connected independently by a resistive-inductive resonant shunting circuit. The folding structure extends the propagation path of elastic waves, while its structure size remains quite small. Propagation of coupled extension-flexural elastic waves is studied by the classical laminated beam theory and transfer matrix method. The theoretical model is further verified with the finite element method(FEM). The effects of geometrical and circuit parameters on the band gaps are analyzed. With only 4 unit cells, the folding beam-type piezoelectric phononic crystal generates two Bragg band gaps of 369 Hz to1 687 Hz and 2 127 Hz to 4 000 Hz. In addition, between these two Bragg band gaps, a locally resonant band gap is induced by resonant shunting circuits. Appropriate circuit parameters are used to join these two Bragg band gaps by the locally resonant band gap.Thus, a low-frequency and broad band gap of 369 Hz to 4 000 Hz is obtained.

Mechano-chemical selections of two competitive unfolding pathways of a single DNA i-motif

The DNA i-motif is a quadruplex structure formed in tandem cytosine-rich sequences in slightly acidic conditions. Besides being considered as a building block of DNA nano-devices, it may also play potential roles in regulating chromo- some stability and gene transcriptions. The stability of i-motif is crucial for these functions. In this work, we investigated the mechanical stability of a single i-motif formed in the human telomeric sequence 51-（CCCTAA）3CCC, which revealed a novel pH and loading rate-dependent bimodal unfolding force distribution. Although the cause of the bimodal unfolding force species is not clear, we proposed a phenomenological model involving a direct unfolding favored at lower loading rate or higher pH value, which is subject to competition with another unfolding pathway through a mechanically stable inter- mediate state whose nature is yet to be determined. Overall, the unique mechano-chemical responses of i-motif-provide a new perspective to its stability, which may be useful to guide designing new i-motif-based DNA mechanical nano-devices.

Plants and Animals as Concept Generators for the Development of Biomimetic Cable Entry Systems

Many animals and plants have high potential to serve as concept generators for developing biomimetic materials and structures. We present some ideas based on structural and functional properties of plants and animals that led to the development of two types ofbiomimetic cable entry systems. Those systems have been realized on the level of functional demonstrators.

Design and fabrication of a sub-millimeter multi-beam folded waveguide structure

A novel multi-beam folded waveguide(MBFW) circuit,which can enhance the output power and interaction efficiency of sub-terahertz(THz) traveling wave tube(TWT),is presented in the paper. Operating with fundamental mode and multiple electron beams means that a larger beam current can be used for a higher output power. The characteristics of the MBFW structure are analyzed and optimized. Compared with the single-beam folded waveguide(SBFW) TWT,the output power of the MBFW TWT increases from 3.64 W to 25.45 W at 140 GHz and its electronic efficiency increases from 1.06% to 7.4% under the conditions of an input peak power of 10 m W,a beam voltage of 9.55 k V and a current of 12 m A. The optimized MBFW structure can be successfully fabricated by micro milling,with dimension errors below expectation,and the measured transmission characteristics are in good agreement with the design.

How the “Folding Funnel” Depends on Size and Structure of Proteins?A View from the Scoring Function Perspective

It has been well accepted that the folding energy landscape may resemble a funnel according to the theory of protein folding. This theory of ＂folding funnel＂ has been extensively studied and thought to play an important role in guiding the sampling process of the protein folding and refinement in protein structure prediction. Here, we have investigated the relationship between the ＂funnel likeness＂ of protein folding and the size/structure of the proteins based on a set of non-homologous proteins we have recently evaluated using a statistical mechanicsbased scoring function ITScorePro. It was found that larger proteins that consist of more helix/sheet structures tend to have a higher score-Root Mean Square Deviation（RMSD） correlation（or a more funnel like energy landscape）.Another measurement in protein folding, Z-score, has also shown some correlation with the size of the proteins.As expected, proteins with a better ＂olding funnel likeness＂（or score-RMSD correlation） tend to have a betterpredicted conformation with a lower RMSD from their native structures. These findings can be extremely valuable for the development and improvement of sampling and scoring algorithms for protein structure prediction.

Tunable electron and phonon properties of folded single-layer molybdenum disulfide

A unique feature of transition metal dichalcogenides is their single-layer form, which enables folding. Although folding has been found to significantly affect the photoluminescence spectrum and some in-plane properties, only limited insight has been gained on how to modulate those properties. In this report, we examine the structure of folds of a single sheet of MoS2 and the dependence of the ground-s tate electronic and phonon transport properties on the wrapping length. As the folded structure is effectively a bilayer that terminates in a loop, the wrapping length modulates the relative size of the bilayer region to the closed loop along the edge. A combination of computational methods, including approaches based on variational mechanics, classical potentials, and density functional theory, are employed. Highly accurate calculations of the reference folded structure are first carried out to show that the folded structure is largely insensitive to the wrapping length. The folded structures are subsequently used to estimate the electronic band gap, which is found to vary significantly as a function of the wrapping length, and converges from below to the limit value corresponding to an infinite bilayer. The gap values range from 0.43 to 1.09 eV, with a crossover to an indirect gap, which suggests that the transitions must be lattice-assisted, similar to the transitions in the bilayer and bulk forms. However, the phonons, while affected by the formation of the folded structure, are insensitive to the wrapping length. In fact, the overall thermal transport behavior along the folding axis is unchanged. The possibility of modulating the gap value while keeping the thermal properties unchanged opens up new exciting avenues for further applications of this emerging material.

Design of a novel mixer with high gain and linearity improvement for DRM/DAB applications

This paper focuses on a new design of a down-conversion mixer for a low-IF wideband receiver.Based on the folded structure and differential multiple gated transistor（DMGTR） technique,a novel quadrature mixer with a high conversion gain,a moderate linearity,and a moderate NF is proposed.The mixer is designed and implemented in a 0.18-m CMOS process,and can operate in a frequency range from 150 kHz to 1.5 GHz.The circuit performance is confirmed by both simulation and measurement results.The measurement results exhibit a peak conversion gain of 13.35 dB,a high third order input referred intercept point of 14.85 dBm,and a moderate single side band noise figure of 10.67 dB.Moreover,the whole quadrature mixer core occupies a compact die area of 0.122 mm2.It consumes a current of 3.96 mA（excluding the output buffers） under a single supply voltage of 1.8 V.

Probe Staurosporine Drug Binding Site on Protein Kinase by PFSC

We used a new approach,protein folding shape code（PFSC）,to predict the potential staurosporine binding sites in protein kinases.Firstly,all available three dimensioned（3D） structures of protein kinases in protein databank（PDB） were converted into one-dimensional PFSC description,based on which a PFSC-kinome library was constructed.Secondly,a set of protein kinase-staurosporine complexes were analyzed to define the common structural features of the binding sites.Thirdly,the structural features of the staurosporine binding sites were used to virtually screen the PFSC-kinome library to predict multiple protein receptors that have potential binding capacity for staurosporine.Collectively,the development of the similar method for predicting drug binding site demonstrates that virtual screening protein database can provide valuable information on drug discovery and understanding of pharmacological pathways.