A simple method to calibrate the temperature effect for the calculation of gas permeability

Temperature plays an important role in the gas permeability test. A small temperature variation still exists in the experimental process since the temperature control device cannot strictly maintain a constant temperature. This can further affect the accuracy of the gas permeability. To solve this problem, a simple method based on the ideal gas equation of state is introduced to calibrate the gas pressure variation because of the temperature effect. We verified the calibration results through sever?al examples, and the results proved the feasibility and effectiveness of the method. In particular, this method is particularly effective for low permeability materials in long-term gas permeation tests.

Latchable microfluidic valve arrays based on shape memory polymer actuators

Latchable microfluidic valve arrays taking advantage of the shape memory polymer's multiple stable shapes and large change in stiffness for a small temperature variation.

Experimental Study on Hygrothermal Deformation of External Thermal Insulation Cladding Systems with Glazed Hollow Bead

This research analyzes the thermal and strain behavior of external thermal insulation cladding systems (ETICS) with Glazed Hollow Beads (GHB) thermal insulation mortar under hygrothermal cycles weather test in order to measure its durability under extreme weather (i.e., sunlight and rain). Thermometers and strain gauges are placed into different wall layers to gather thermal and strain data and another instrument measures the crack dimensions after every 4 cycles. The results showed that the finishing coat shrank at early stage (elastic deformation) and then the finishing coat tends to expand and become damaged at later stage (plastic deformation). The deformation of insulation layer is similar to that of the finishing coat but its variation amplitude is smaller. Deformation of substrate expanded with heat and contracted with cold due to the small temperature variation. The length and width of cracks on the finishing coat grew as the experiment progressed but with a decreasing growth rate and the cracks stopped growing around 70 cycles.

Criticality in reactors under domain or external temperature perturbations

The conditions for the onset of thermal runaway in reactors with small non-uniformities is investigated. The reaction is modelled by an Arrhenius heat generation term with a finite activation energy and the dimensionless temperature, u 0 , is taken to satisfy a nonlinear equation of the form Δ u 0 + λ 0 F ( u 0 ) = 0, x ∈ D ; ∂ v u 0 + bu 0 = 0. x ϵ∂ D . We investigate three classes of perturbations of this problem. First, we treat a small temperature variation maintained on the boundary of the domain. Secondly, we consider a small distortion of the boundary of a circular cylindrical domain, and thirdly, we analyse the effect of a small hole in the domain. In each case we derive asymptotic expansions for the critical Frank-Kamenetskii parameter, λ c ( ϵ ), where ϵ is a measure of the size of the perturbation. A numerical scheme is then used to determine numerical values for the coefficients in the asymptotic expansion of λ c . Finally, some of the asymptotic results are compared with corresponding numerical results obtained from a full numerical solution of the perturbed problem.

The phosphorus-31 and metal nuclear magnetic resonance spectra of complexes of tin(II) and lead(II) with tricyclohexylphosphine oxide, sulfide, and selenide

The new stannous and plumbous complexes M(OP(C6H11)3)n2+ (n = 2 or 3, M = Sn or Pb) and [M(SP(C6H11)3)x(SeP-(C6H11)3)3−x]2+ (M = Sn or Pb) have been prepared in SO2 solution and characterized by their reduced temperature slow-exchange 31P and metal (119Sn or 207Pb) nmr spectra. No evidence could be found for complexes in which both OP(C6H11)3 and EP(C6H11)3 (E = S or Se) are coordinated to tin(II) or lead(II). The same pattern of chemical shifts is found in the 119Sn and 207Pb nmr spectra: δM(M(OP(C6H11)3)22+) < δM(M(OP(C6H11)3)32+ < δM(M(SP(C6H11)3)32+) < δM(M(SeP(C6H11)3)32+) and a monotonic but non-linear variation of δM with x for [M(SP(C6H11)3)x(SeP(C6H11)3)3−x]2+. From M(AsF6)2 in SO2 as reference, the range of the metal chemical shifts is 999–2079 ppm and 2407–7707 ppm in the 119Sn and 207Pb nmr spectra respectively. In the 31P nmr spectra, all of the appropriate two-bond M—P couplings are observed, but the fine structure expected from coupling to 31P could not always be observed in those metal nmr spectra which were measured at high field; it is suggested that these metal nmr spectra are "smeared out" by a combination of large temperature sensitivity of the metal chemical shifts and the small temperature variation allowed by the nmr spectrometer temperature controller and/or diffusion along any temperature gradients present along the length of the nmr sample.