AUTOMATIC PLANNING OF ASSEMBLING ORDER FROM ASSEMBLY DRAWING

It is important to plan the assembling order automatically in order to reach assembling mechanization, especially intellectualization. The foundation of assembling order is how to understanding assembly drawing automatically, namely the capacity of machine “drawing reading”. This paper introduces the general structure of ESUAD(Expert System of Understanding Assembly Drawing) system, its knowledge representation, the automatical understanding of assembly drawing, the plan of assembling order. Finally the paper will give the experiment result.

Mechanically Strong and Flame‑Retardant PBO/BN/MXene Nanocomposite Paper with Low Thermal Expansion Coefficient,for Efficient EMI Shielding and Heat Dissipation

As portable and wearable electronic devices are rapidly developing,there is an urgent need for flexible and robust thermally conductive electromagnetic interference shielding materials to address the associated electromagnetic pollution and overheating issues.Herein,multifunctional poly(p-phenyl-2,6-phenylene bisoxazole)nanofiber/boron nitride nanosheet/Ti_(3)C_(2)T_(x)MXene nanosheet(PBO/BN/MXene)composite papers are prepared by a gel microparticle-mediated ordered assembly process with the aid of vacuum-assisted filtration.Nacre-like“brick and mortar”structure,segregated structure and sandwich structure are integrated into the composite paper,so that efficient thermally and electrically conductive networks have been established.When the BN and MXene contents are 29.2 wt%and 41.7 wt%,the 13μm thick composite paper exhibits an EMI shielding performance of 31.8 dB and a thermal conductivity of 26.1 W/mK,markedly superior to those of the control samples without the ordered structures.Meanwhile,because of the unique architecture and inherent advantages of the building blocks,the composite paper exhibits extremely low coefficient of thermal expansion(~1.43 ppm/K),excellent mechanical properties,and outstanding thermal stability and flame retardance,making it highly advantageous for practical applications in electronic devices.This work offers a promising approach for fabricating high-performance multifunctional composites by constructing efficient filler networks.

Sharp scattering spectra induced brilliant and directional structural colors

Structural color materials,which generate colors through the interaction between light and nano-microstructures,have always been research hotspots in the fields of display,anticounterfeiting and stimuli-responsive materials.Structural colors based on scattering have received increasing attention due to their wider viewing angles than that originating from the specular reflection of photonic crystals.However,the wide scattering spectrum of an amorphous structure leads to lower purity and brightness of the appeared colors.Few researchers have focused on the scattering of ordered structures due to their strong reflection and diffraction in the visible regions.In this work,by building ordered films(OFs)using SiO2 spheres(refractive index n=1.46)with a diameter of 300–500 nm,for the first time,sharp scattering spectra with narrow full width at half-maximum(FWHM,24 nm)were generated.Importantly,under ambient light,brilliant colors covering the entire visible region can be observed,and a formula was proposed to calculate the scattering spectra of OFs.Moreover,rainbow structural color was realized under irradiation of the nonparallel light,and full-spectrum structural color patterns were fabricated using building blocks with a single particle size by a spraying method.Finally,a composite structure was constructed to explore possibilities in the field of flexible transparent displays.

Recent Progress in Exploiting Small Molecule Peptides as Supramolecular Hydrogelators

Small molecule peptides and their derivatives are an emerging class of supramolecular hydrogelators that have attracted rapidly growing interest in the fields of drug delivery and regenerative medicine due to their inherent biodegradability and biocompatibility, as well as versatility in molecular design and ease of synthesis. Built upon the directional, intermolecular interactions such as hydrogen bonding and π-π stacking, peptide-based molecular units can associate in aqueous solution into filamentous assemblies of various sizes and shapes. Under appropriate conditions, these filamentous assemblies can percolate into a 3D network with materials properties tailorable for specific biomedical applications. In this review, we survey the literature published over the past three years in the development of peptide-based hydrogelators for biomedical applications. We highlight several representative examples and center our discussion on the fundamentals of molecular design, assembly, and gelation conditions.

ECONOMY

Helicopter Purchase A Chinese consortium has ordered100 H135 twin-engine helicopters from Airbus Helicopters and will build a fnal assembly line in Qingdao,east China’s Shandong Province,Airbus said on June 13.In a press release,Airbus said that the consortium is made up of China Aviation Supplies Holding Co.,Qingdao United General Aviation Industrial Development Co.and CITIC Offshore Helicopter Co.Ltd.