2,3,5,6-Tetra­methoxy­piperazine-1,4-dicarbaldehyde

The asymmetric unit of the title compound, C10H18N2O6, contains two halves of two independent centrosymmetric mol­ecules with almost identical conformations. Weak inter­molecular C—H⋯O hydrogen bonds consolidate the crystal packing

Back-to-back aperture- and gap-coupled discontinuities integration for band-pass filter design

A new class of back-to-back integrated aperture- and gap-coupled discontinuities is proposed for substrate-integrated waveguide band-pass filter design. The developed structure is shown to take advantage of both discontinuities in the design of cavity and/or planar resonators with an optimum performance including higher quality factor accompanied by transmission zero realisation, wider upper stop-band with second harmonic suppression, and a considerable size reduction. The measured unloaded quality factor has been increased by a ratio of 60% in comparison to the conventional gap-coupled structures

Promotion of Tunneling Performance in Locally Semi-Hard to Hard Conglomerate Lenses, Case of Esfahan Historical City Subway Project

The highly inhomogeneous nature of the river deposits in central Esfahan induced unforeseen problems for tunneling of 2×5 km long of middle section of the Esfahan Subway Project. A noticeable phenomenon in these course grained fluvial (river) deposits is the locally cementation of the soil particles by a calcium carbonate binder and formation of some semi-hard to hard conglomerate lenses. This unique phenomenon is named locally as “Sovord” rock and could be seen just in semi-aired regions as central Iran. Two 6.89 m diameter EPBTBM machines were employed to excavate shallow tunnels in the vicinity of fragile structures of the old city. The main unwanted impacts of this highly cohesive pseudo-rock were noticed as high vibration, temperature raising, tunnel face instability, low rate of machine’s advance, early tools damage and finally great cutter-head damage after the first major collision with this unpredicted phenomenon. We analyzed geotechnical characteristics of this material and the corresponding effects on face supporting pressure, foaming agents, soil conditioning process and operational policy. Lowering the cylinder thrust force, ≤9000KN, improving the cutting wheel rotation speed, ≥2.5RPM, using some anti-abrasive foaming agents, ABR2 lubricants, and periodic tools inspection schedule was considered as solution for the indicated problem

Use of concentric hele-shaw cell for the study of displacement flow and interface tracking in primary cementing

We present our new designed concentric Hele-Shaw cell geometry with dynamic similarity to a real field wellbore annulus during primary cementing, and then, the results of displacement flow of Newtonian and yield-stress non-Newtonian fluids in it are described. The displacement stability and efficiency, the effect of back, front, and side boundaries on displacement, bypassing pockets of displaced yield-stress fluid in displacing fluid, and the behavior of pressure gradients in the cell are investigated. Applications of intermediate buoyant particles with different sizes and densities intermediate between those of successively pumped fluids for tracking the interface between the two displaced and displacing fluids are examined. The main idea is to upgrade this concentric Hele-Shaw cell geometry later to an eccentric one and check the possibility of tracking the interface between successive fluids pumped in the cell. Successful results help us track the interface between drilling fluid and spacer/cement during primary cementing in wells penetrating a CO2 storage reservoir and decreasing the risk of CO2 leakage from them.publishedVersio

Pipe Viscometer for Continuous Viscosity and Density Measurement of Oil Well Barrier Materials

The barrier material is a crucial component for wells, as it provides mechanical support to the casing and prevents the uncontrolled flow of formation fluids, ensuring zonal isolation. One of the essential prerequisites for the success of cementing an oil and gas well is the efficient removal of in-situ fluids and their adequate replacement by the barrier material. The quality of the mud displacement is affected by both the density and the viscosity hierarchy among subsequent fluids. Consequently, accurate and reliable measurement of fluid properties can help ensure consistent large-scale mixing of cementing fluids and verification that the properties of the mixed fluid are according to plan. In this paper, we investigate the implementation of a pipe viscometer for future automated measurements of density and viscosity of materials for zonal isolation and perform a sequential validation of the viscometer that starts with small-scale batch mixing and characterization of particle-free calibration liquids, followed by conventional Class G cement and selected new barrier materials. Finally, a larger-scale validation of the pipe viscometer was performed by integrating it into a yard-scale batch mixer for in-line characterization of expanding Class G oilwell cement mixing. In all cases, flow curves derived from pipe viscosity measurements were compared with offline measurements using a rheometer and a conventional oilfield viscometer. After a series of measurements and comparisons, the investigated in-line measurement system proved adequate for viscosity estimation. The flow curve of the barrier materials showed results similar to measurements using a conventional viscometer, validating the proposed test configuration to continuously measure the rheological behavior of the barrier material. The pipe viscometer flow curves are generally found to be in good quantitative agreement with independent viscometer characterization of the fluids, although some of the pipe viscometer measurements likely exhibited entrance length effects. Future improvements to the pipe viscometer design involve the assessment of even longer pipe sections to allow full flow development at the highest shear rate range and possibly different pipe diameters to improve the measurement resolution of low-shear rate viscosity.publishedVersio

Moisture content on some engineering properties of celery (Apium Graveolens L) seeds

The study was conducted to investigate some physical properties of celery seed at various moisture levels.  The average length, width, thickness and 1000-seeds mass were 0.571, 0.429, 0.295 mm and 0.792 g, respectively, at moisture content of 5.24% (d.b).  Length, width and thickness distributions of the seeds were modeled using Generalized Extreme Value, lognormal and Weibull distributions.  Results showed that to model length of the seeds, lognormal distribution had the best performance while to model the width of the seeds Weibull distribution had the best performance.  True density has increase from 892.02 to 931.42 kg/m3 when the moisture content increased from 5.24% to 20.25% (d.b).  The angle of static friction increased from 28.45 to 39.66°, 25.15 to 34.84°, 19.57 to 27.07° and 16.72 to 19.720° for plywood, rubber, iron and galvanized metal, respectively, as the moisture content increases from 5.24% to 20.25% (d.b).  The pouring angle of repose increased from 34.70 to 39.12°, 33.37 to 36.37°, 30.59 to 33.33° and 27.16 to 29.45° for plywood, rubber, iron and galvanized metal , respectively, as the moisture content increases from 5.24% to 20.25% (d.b).  The Hele-Shaw angle of repose increased from 32.65 to 35.25°, 30.35 to 32.77°, 27.81 to 30.03° and 24.72 to 26.61° for plywood, rubber, iron and galvanized metal , respectively, as the moisture content increases from 5.24% to 20.25% (d.b)

Determining dimensional, gravimetrical and frictional properties of red radish seeds (Raphanus Sativus L.) as a function of moisture content

To design the planting, separating, threshing, sizing and packing machines for agricultural products, physical and mechanical properties of the products should be known. In this paper, some physical properties of red radish seeds were studied. Dimensional parameters, when moisture content equals to 5.65% based on dry bases (d.b), were measured using image processing technique. Effects of moisture content on gravimetrical and frictional properties of the seeds, including mass of single seed, 1000-unit seed, bulk density, true density, porosity, static coefficient of friction on various surfaces, and angle of repose based on pouring, Hele-Shaw, empting and filling methods were studied. Effects of volume of the container (150, 350, 550 and 750 mL) and height of fall on bulk density and porosity of the radish seeds when moisture content equals to 5.65% (d.b) were studied. Also length, width, thickness and mass distributions of radish seeds were modeled using Gamma, Generalized Extreme Value and Weibull distributions. Results showed that length, width and thickness of the seeds ranged from 0.660 to 0.900 mm, 0.524 to 0.763 mm and 0.490 to 0.759 mm, respectively. With increasing volume of the container from 150 to 550 mL, bulk density of the seeds increased; but with increasing volume of the container from 550 to 750 mL, bulk density of the seeds decreased. With increasing volume of the container from 150 to 550 mL, bulk density of the seeds increased; but with increasing volume of the container from 550 to 750 mL, bulk density of the seeds decreased. With increasing moisture content from 5.65 to 21.71% (d.b) , bulk and true density of the seeds decreased from 694.807 to 654.889 kg/m3 and 1141.810 to 1057.795 kg/m3; but with increasing moisture content from 5.65% to 21.71% (d.b) , 1000-unit mass increased from 6.98 to 7.17 g

The prevalence and predicting factors of pulmonary thromboembolism in patients with exacerbated chronic obstructive pulmonary disease

Introduction: The risk of pulmonary thromboembolism (PTE) in patients with exacerbated chronic obstructive pulmonary disease(e-COPD) is higher than in non-COPD states. The study aimed to evaluate the prevalence and the parameters that are critical forfinding the incidence of PTE in patients with e-COPD. Material and methods: This cross-sectional study was performed on 68 consecutive patients with the e-COPD, referred to thePulmonary Disease Department at the Shariati Hospital in Tehran between 2013 and 2014. In addition to collecting data on thehistory of disease and physical examination, arterial blood sampling, spirometry, electrocardiography and echocardiography wereperformed for all patients. All subjects underwent computed tomography pulmonary angiography (CT-PA) as a method of choicefor diagnosing PTE. Results: Out of 68 cases, five (7.4%) had CT angiography findings suggesting PTE. These patients were all male and had a highermean age (79 vs. 65 years), lower mean systolic blood pressure (88.36 vs. 118.33 mmHg), and a higher mean heart rate (133.12vs 90.33 beats/min), compared to e-COPD patients without PTE. Arterial blood gas analysis in individuals with PTE demonstrateda lower HCO3 (2.33 vs. 9.44 mEq/l) and PCO2 (44.35 vs. 51.43 mm Hg) levels. The mean left ventricular ejection fraction (LVEF)was lower in patients with PTE (34.14 ± 4.49% vs. 46.94 ± 8.27%). Conclusion: The prevalence of PTE in our series of patients with e-COPD was 7.4%. According to the study results, male gender,advanced age, hypotension, tachycardia, and respiratory alkalosis are factors indicating possible PTE among subjects with e-COPD