Oil and gas pipeline networks require the periodic inspection of their infrastructure, which can cause gas and oil leakage with several damages to the environment and human health. For this, non-destructive testing (NDT) techniques of low-cost and easy implementation are required. An option is the metal magnetic memory (MMM) method, which could be used for real-time monitoring defects of ferromagnetic structures based on the analysis of self-magnetic leakage fields distribution around each defect. This method only requires magnetic sensors with high resolution and a data processing system. We present a measurement system of tangential and normal MMM signals of three rectangular defects of an ASTM A-36 steel pipe. This system is formed by a magnetoresistive sensor, an Arduino nano and a virtual instrumentation. The measured magnetic signals have non-uniform distributions around the rectangular defects, which have small differences with respect to the results obtained of a 2D magnetic dipole model. The size of each rectangular defect is related to the amplitude and shape of its tangential and normal MMM signals. The proposed system could be used for real-time monitoring of the size and location of rectangular defects of ferromagnetic pipes. This system does not require expensive equipment, operators with high skill level or a special treatment of the ferromagnetic samples.

Microelectromechanical system (MEMS)-based piezoelectric energy harvesting (PEH) devices can convert the mechanical vibrations of their surrounding environment into electrical energy for low-power sensors. This electrical energy is amplified when the operation resonant frequency of the PEH device matches with the vibration frequency of its surrounding environment. We present the electromechanical modeling of two MEMS-based PEH devices to transform the mechanical vibrations of domestic washing machines into electrical energy. These devices have resonant structures with a T shape, which are formed by an array of multilayer beams and a ultraviolet (UV)-resin seismic mass. The first layer is a substrate of polyethylene terephthalate (PET), the second and fourth layers are Al and Pt electrodes, and the third layer is piezoelectric material. Two different types of piezoelectric materials (ZnO and PZT-5A) are considered in the designs of PEH devices. The mechanical behavior of each PEH device is obtained using analytical models based on the Rayleigh–Ritz and Macaulay methods, as well as the Euler–Bernoulli beam theory. In addition, finite element method (FEM) models are developed to predict the electromechanical response of the PEH devices. The results of the mechanical behavior of these devices obtained with the analytical models agree well with those of the FEM models. The PEH devices of ZnO and PZT-5A can generate up to 1.97 and 1.35 µW with voltages of 545.32 and 45.10 mV, and load resistances of 151.12 and 1.5 kΩ, respectively. These PEH devices could supply power to internet of things (IoT) sensors of domestic washing machines.

Ferromagnetic pipes are widely used for fluid transportation in various industries. The failure of these ferromagnetic pipes due to surface defects can generate industrial accidents, economic losses, and environmental pollution. Non-destructive testing techniques are required to detect these surface defects. An alternative is the metal magnetic memory (MMM) method, which can be employed to detect surface flaws in ferromagnetic structures. Based on this method, we present an analysis of experimental results of the magnetic field variations around five different surface semi-elliptical defects of an ASTM A36 steel pipe. A measurement system of MMM signals is implemented with a rotatory mechanism, a magnetoresistive sensor, a data processing unit, and a control digital unit. The MMM method does not require expensive equipment or special treatment of the ferromagnetic structures. In order to research a potential relationship between the defect sample size and the measured MMM signals, variable defect dimensions are experimentally considered. According to these results, the shape and magnitude of the normal and tangential MMM signals are altered by the superficial semi-elliptical defects. In particular, the maximum and mean tangential components and the maximum and minimum normal components are related to the defect dimensions. The proposed measurement system can be used to study the behavior of magnetic field variations around surface defects of ferromagnetic pipes. This system can be adapted to measure the position and damage level of small defects on the surface of ferromagnetic pipes.

When a student of naval engineering is introduced to issues related to structures of a ship, it is difficult to understand vessel concepts. A graphical user interface (GUI) that helps visually understand the baseline of a ship depending on the pressure, the gravity and tanks level is adequate to accomplish the task with partial ease, quickly and also enjoy the learn experience. This paper describes the development of a user interface for its implementation in the naval Engineering Educational, is designed with structured and modular programming using open source software MyOpenLab©. The goal of this work is calculated longitudinal resistance of the boats, obtaining the diagrams of shear force and bending moment.

The global water crisis represents one of humanity’s most pressing challenges, with over 2 billion people lacking access to safely managed drinking water. This study presents the implementation and evaluation of an innovative air-conditioning condensate recovery system at Building F of the Faculty of Electrical and Electronic Engineering (FIEE), Universidad Veracruzana, Mexico. The system integrates twenty-six 24,000 BTU air-conditioning units across twelve classrooms and two laboratories, recovering approximately 520 L of condensate water daily. An initial physicochemical characterization of the recovered condensate was conducted through pH, electrical conductivity (EC), and total dissolved solids (TDS) measurements. In addition, the dried residue obtained after evaporation of the condensate was examined using semi-quantitative X-ray fluorescence (XRF) analysis. The XRF results describe the relative elemental composition of the dried residue and must not be interpreted as aqueous concentrations or as evidence of compliance with water-quality standards. The recovery system includes a nominal 0.5 µm polypropylene sediment cartridge, activated-carbon filtration, and a Crystolite^® treatment medium. Because paired measurements before and after treatment were not performed, the removal efficiencies of these components were not determined. The recovered water is subsequently stored and processed in a dual-tank configuration: a primary 3300 L storage system and a secondary 200 L tank used to prepare fertilizer-amended condensate for ornamental-plant irrigation. A fully water-soluble monopotassium phosphate fertilizer (MKP, 0 (–52–34) was incorporated at a gravimetric proportion of 1:10 (1 g MKP per 10 g recovered condensate water).