Stabilizing a class of nonlinear parameter-varying systems using interval observer based on a piecewise framework

This article addresses an interval observer-based control for stabilizing a class of nonlinear parameter-varying systems with noisy output by designing a switching surface. An input-dependent interval observer is firstly developed to estimate the lower and upper bounds of the states. Next, a switching-based controller is designed to stabilize the interval observer which implies the stability of the main parameter-varying system. The developed stabilizing switching surfaces are designed based on the outputs of the main system and the bounds of the states of the observer. By choosing an appropriate piecewise Lyapunov function, the closed-loop stability analysis of the interval observer system leads to a set of linear matrix inequalities including stability and Metzler constraints, simultaneously. The effectiveness of the proposed method is verified using the simulation results.     

The effect of heat transfer characteristics of macromolecule fouling on heat exchanger surface: A dynamic simulation study

At the city gate gas pressure reduction stations (CGSs), to prevent natural gas from forming a hydrate in the throttle valve, the natural gas is heated by the heater before reaching the pressure relief valve. Heat exchangers are an essential component of industrial processes that contribute significantly to total system energy. Since the element impacting heat exchanger performance is the fouling process, all fouling processes and models were dynamically simulated in this study. Through coding in the C++ language and simultaneous use of fluent functions, or, in other words, user-defined function (UDF), fouling-related models were defined for this software. The dynamic simulation was performed, and parameters such as fouling strength and layer thickness were calculated. The effects of changing operating conditions, such as gas inlet velocity, surface temperature, and fouling species concentration on fouling growth, were also evaluated. As the concentration of fouling species increased, the fouling rate also increased. The amount of supersaturation and fouling rate increased as the surface temperature increased. Due to the operational limitations of the system, to reduce the fouling rate, the gas inlet velocity should be as high as possible, and the fluid inlet temperature, surface temperature, and concentration of fouling species should be as low as possible. In this study, the required time to reach the efficiency of 70% of the heat exchanger was calculated using the modelling of this chamber, which was equivalent to 190 days. Additionally, the critical thickness of the fouling layer at this time was 3.5 cm.     

The Effect of NaY nano-Zeolite on the Mechanical Properties of Silicon Insoles

Silicon - The chemical composition of the insoles inbounded materials influences some of the mechanical properties of silicon insoles including; tensile strain and modules and moisture adsorption...     

A cloud database route scheduling method using a hybrid optimization algorithm

Cloud computing has appeared as a technology allowing a company to employ computing resources such as applications, software, and hardware to calculate over the Internet. Scholars have paid great attention to cloud computing because of its cutting-edge availability, cost decrement, and boundless applications. A cloud database is a data storage site on the web where the optimal path is spotted to access the needed database. So, placing the ideal path to a database is crucial. The cloud database defined the scheduling problem to choose the perfect route. Cloud database path scheduling is a multifaceted procedure consisting of congestion control, routing list, and network flow distribution. It has a postponement in searching for the needed source route from the cloud database. Offering numerous infinite resources with the growing database workload is an NP-Hard optimization problem where the query request needs optimal schedules to respond to the required services. So, we have used a hybrid cuckoo search (CS) and genetic algorithm (GA), motivated by a social bird's phenomenon, to solve this problem. Integrating genetic operators has dramatically enhanced the balance between the capability of searching and utilization.     

Emulsion Based Nanoarchitectonics for Styrene–Butyl Acrylate Copolymerization upon Pickering Mechanism

Journal of Inorganic and Organometallic Polymers and Materials - The modification of graphene oxide (GO) with octadecylamine was performed to emulsify dimethyl formamide droplets in octane via...     

Two Layer Symmetric Cryptography Algorithm for Protecting Data fromAttacks

Many organizations have insisted on protecting the cloud server from the outside, although the risks of attacking the cloud server are mostly from the inside. There are many algorithms designed to protect the cloud server from attacks that have been able to protect the cloud server attacks. Still, the attackers have designed even better mechanisms to break these security algorithms. Cloud cryptography is the best data protection algorithm that exchanges data between authentic users. In this article, one symmetric cryptography algorithm will be designed to secure cloud server data, used to send and receive cloud server data securely. A double encryption algorithm will be implemented to send data in a secure format. First, the XOR function will be applied to plain text, and then salt technique will be used. Finally, a reversing mechanism will be implemented on that data to provide more data security. To decrypt data, the cipher text will be reversed, salt will be removed, and XOR will be implemented. At the end of the paper, the proposed algorithm will be compared with other algorithms, and it will conclude how much better the existing algorithm is than other algorithms.     

Coordination of bioenergy supply chains under government incentive policies: a game-theoretic analysis

Clean Technologies and Environmental Policy - Biomass as an abundant renewable energy source can play a vital role in controlling the greenhouse gas emissions. The distributed nature of biomass and...     

Continuous Production of Highly Functional Vascularized Hepatobiliary Organoids from Human Pluripotent Stem Cells using a Scalable Microfluidic Platform

“Organoid medicine” has rapidly progressed over the past decade as a new class of therapeutics with high functionality and complexity for addressing unmet medical needs such as effective treatment of patients suffering from chronic liver disease using liver organoids. Here, scalable and xeno-free integrated differentiation platforms are established to generate hepatic progenitors, mesenchymal stromal cells, and endothelial cells using individual human pluripotent stem cell lines as starting cell types for vascularized liver organoids generation. A scalable microfluidic system is developed to continuously generate cells-loaded microcapsules with self-biodegradable 4-arm-PEG-MMP1-sensitive peptide hydrogel as shell material, to support cells proliferation, self-condensation, and liver organoids generation through self-organization. Self-organized vascularized hepatobiliary organoids (VHOs) containing interconnected biliary networks and vascular structures are generated after optimizing the co-culture conditions inside hydrogel microcapsules and transferring the organoids to 3D dynamic suspension culture for further maturation. The VHOs show key functional features similar to the fetal and adult liver tissue including the expression of liver-specific marker genes, the ability to perform main liver metabolic functions, and inducing drug metabolism. The established platforms can be beneficial to the mass production of human liver organoids for liver organoid medicine and the development of safe, effective, and personalized drugs.     

Exact analytical solution of forced convection through a porous-saturated duct

In the current paper, the effect of a magnetic field on the fully developed forced convective flow and heat transfer is studied. An exact solution is extracted when the flow in the porous medium is governed by the Brinkman–Forchheimer Extended Darcy model. First, the problem formulation is explained to obtain a new system of mathematical formulation. Then, by utilizing the properties which are imposed into the problem, the exact closed-form analytical solution of the problem is explored. Finally, the main results are illustrated to show the impact of the porous media-shaped parameter, magnetic parameter, Forchheimer number, and viscosity ratio. It should be mentioned that the asymptotic results achieved in this study were compared with the exact results and it is found that they are in good agreement.     

Thermoelectric properties of hot-pressed Ruddlesden-Popper phases CaO(CaMnO3)m

We investigated the Ruddlesden-Popper series CaO(CaMnO₃)_m with m = 1, 2, 3, ∞, to study the impact of the varying amounts of CaO layers on their thermoelectric properties. Previous studies showed that highly dense samples are difficult to obtain due to the refractory nature of these materials. In this study, we managed to obtain dense pellets during a classical hot-pressing step, if and only if the samples were subjected to extended ball-milling prior to pressing, resulting in crystallite sizes of 30–35 nm after hot-pressing. The sample with the largest amount of CaO layers (m = 1) had the lowest electrical and thermal conductivity, and the highest Seebeck coefficient, as predicted. Ultimately the perovskite CaMnO₃ (m = ∞, no CaO layers) exhibited the best thermoelectric properties.