Asymmetric Part Research Articles

The structure of tetranuclear zirconium pivalate ZR<sub>4</sub>O<sub>2</sub> [(CH<sub>3</sub>)<sub>3</sub>CCO<sub>2</sub>]<sub>12</sub> according to X-ray diffraction analysis and quantum chemical calculations

The crystal and molecular structure of a polynuclear pivalate complex obtained by the interaction of ZrCl4 with pivalic acid was determined by X-ray diffraction analysis. The compound C71H124O28Zr4 (compound 1) crystallizes in the monoclinic crystal system. The crystal structure was refined in the nonstandard space group I2. The asymmetric part of the structure includes three Zr atoms, six pivalate ligands, a bridging µ3-O oxygen atom, as well as disordered crystallization molecules of pivalic acid with an occupancy of 50% and benzene with an occupancy of 50%. The zirconium complex molecule is a tetranuclear cluster that contains three types of Zr atoms that differ in ligand environment. Comparison of the results of quantum chemical calculations of the model reaction ZrCl4 with acetic acid with the literature data on reactions of ZrCl4 with aliphatic acids have shown the possibility of the formation of both mononuclear Zr(RCO2)4 and polynuclear clusters in this reaction, which is a new route for obtaining polynuclear zirconium clusters. The structure of the clusters formed depends on the steric properties of carboxylate ligands.

Graphene nanoribbon resonant tunneling diode with dual connection between contacts

In this paper, we numerically study the transport properties of a resonant tunneling diode (RTD) based on graphene nanoribbon (GNR) with an H-type antidote between the contacts. The structure may also be thought of as having two parallel (W-shape) parts connecting the contacts, each having a wider channel region sandwiched between two narrower barrier regions. The energy at which quasi-bound states occur in each part depends on the dimensional parameters of the respective portion in the structure. We study how the transmission through quasi-bound states is influenced by the edge states on the contacts and dimensional parameters such as barrier length and also by the ambient temperature. The results are compared with those of an RTD with a single part connecting the contacts. Transmission peaks at different energies are observed for an RTD with asymmetrical lower and upper parts between the contacts. This is then utilized for the creation of two negative differential resistance (NDR) peaks. For numerical computation, the non-equilibrium Green’s function formalism (NEGF) based on the nearest neighbor tight-binding model is employed.

Numerical and experimental investigation of extrusion processes from coil

The use of coil material as semi-finished product in sheet-bulk metal forming (SBMF), offers the possibility to use high-speed presses and thus to achieve high output quantities. However, compared to industrially established forming of pre-cut blanks, the reduced geometric accuracy of the parts due to the asymmetrical material flow represents a challenge. Against this background, the aim of this study is to gain an in-depth knowledge on the influence of the process setup on the material flow direction and on the forming of geared functional parts. A combined numerical-experimental approach of each a lateral and a backward extrusion process of a DC04 sheet metal ( t0 = 2 mm) is applied for a fundamental process analysis. For this purpose, process-dependent causes for the asymmetric part forming are analyzed by means of material flow simulations. Subsequently, the numerical results are verified experimentally in terms of the part geometry, the process force and grain structural changes. Based on the numerical and experimental results, cause-effect relations between material flow, part accuracy and tool load are derived. In addition, the transferability of the causes of the asymmetric material flow to processes with different primary material flow directions and part geometries is verified. The findings facilitate the future counteraction of asymmetrical material flow in SBMF from coil, which in turn leads to enhanced component quality.

Asymmetric self-interacting dark matter with a canonical seesaw model

We study the possibility of generating dark matter (DM) and baryon asymmetry of the Universe (BAU) simultaneously in an asymmetric DM framework, which also alleviates the small-scale structure issues of cold DM. While the thermal relic of such self-interacting DM remains underabundant due to efficient annihilation into light mediators, a nonzero asymmetry in the dark sector can lead to the survival of the required DM in the Universe. The existence of a light mediator leads to the required self-interactions of DM at small scales while keeping DM properties similar to cold DM at large scales. It also ensures that the symmetric DM component annihilates away, leaving the asymmetric part in the spirit of cogenesis. The particle physics implementation is done in canonical seesaw models of light neutrino mass, connecting it to the origin of DM and BAU. In particular, we consider type-I and type-III seesaw origin of neutrino mass for simplicity and minimality of the field content. We show that the desired self-interactions and relic of DM together with BAU while satisfying relevant constraints lead to strict limits on DM mass O(GeV)≲MDM≲460 GeV. In spite of being a high-scale seesaw, the models remain verifiable in different experiments, including direct and indirect DM searches as well as colliders. Published by the American Physical Society 2024

Influence of material in sheet-bulk metal forming from coil

AbstractSheet-bulk metal forming (SBMF) represents an innovative approach for the efficient manufacturing of functional integrated parts from sheet metal by applying bulk forming processes to sheet metal. It combines the advantages of part weight optimization and process chain shortening. In view of the increasing demand for functionally integrated components, the forming from coil offers an economical possibility to produce high output rates. Nevertheless, an underfilling of functional elements as well as an asymmetric part forming are current challenges. In order to apply SBMF from coil in industrial contexts, it is necessary to understand the causes of these process limits and to develop measures for improving the forming of functional elements and thereby push existing forming limits. In this paper, both a lateral and a backward extrusion process from coil for the forming of internal and external geared SBMF parts are investigated to develop a fundamental process understanding. In a combined numerical-experimental approach, the influence of the flow behavior of different materials as well as the impact of the main material flow direction of the process on the dimensional part accuracy is analyzed. This enables the evaluation of fundamental material-related dependencies and influences regarding the geometrical part accuracy, the mechanical component properties and the tool load for forming of the conventional deep-drawing steel DC04 (t0 = 2 mm), a high-strength steel material (HC260LA) and an aluminum alloy (AA6082 T6). Based on these findings, measures for material flow control are identified and investigated to counteract the challenges of SBMF from coil. These findings permit the identification of potential transferability of the identified cause-effect mechanisms to different processes, component geometries and materials. Thereby, in particular, an increase in coil width as well as lower a strain hardening behavior of the material offers the possibility to improve the geometrical accuracy of the components.

WBSP: Addressing stragglers in distributed machine learning with worker-busy synchronous parallel

Parameter server is widely used in distributed machine learning to accelerate training. However, the increasing heterogeneity of workers’ computing capabilities leads to the issue of stragglers, making parameter synchronization challenging. To address this issue, we propose a solution called Worker-Busy Synchronous Parallel (WBSP). This approach eliminates the waiting time of fast workers during the synchronization process and decouples the gradient upload and model download of fast workers into asymmetric parts. By doing so, it allows fast workers to complete multiple steps of local training and upload more gradients to the server, improving computational resource utilization. Additionally, the global model is only updated when the slowest worker uploads the gradients, ensuring the consistency of global models that are pulled down by all workers and the convergence of the global model. Building upon WBSP, we propose an optimized version to further reduce the communication overhead. It enables parallel execution of communication and computation tasks on workers to shorten the global synchronization interval, thereby improving training speed. We conduct theoretical analyses for the proposed mechanisms. Extensive experiments verify that our mechanism can reduce the required time to achieve the target accuracy by up to 60% compared with the fastest method and increase the proportion of computation time from 55%–72% in existing methods to 91%.

ТЕОРЕТИЧЕСКОЕ И ЭКСПЕРИМЕНТАЛЬНОЕ ИССЛЕДОВАНИЕ ПРОИЗВОДИТЕЛЬНОСТИ ЗУБЧАТОГО БУНКЕРНОГО ЗАГРУЗОЧНО-ОРИЕНТИРУЮЩЕГО УСТРОЙСТВА ДЛЯ АСИММЕТРИЧНЫХ ДЕТАЛЕЙ ТЕЛ ВРАЩЕНИЯ

The article presents the results of a theoretical and experimental study of the performance of a mechanical disk gear hopper feeding-orienting device with an annular orientator for asymmetric parts of rotation bodies. For theoretical description of productivity, mathematical model of probability of gripping asymmetric parts with end face in form of truncated cone is presented, with the help of which it becomes possible to determine actual productivity of feeding-orienting device and estimate of influence on it of geometric parameters of parts, structural and kinematic parameters of hopper feeding-orienting device. Using the developed mathematical model, the parameters of the bunker feeding-orienting device were determined, at which its feed rate would be maximum. To confirm the adequacy and correctness of the developed mathematical model of capture probability to describe the feed rate, the results of experimental studies on the layout of the feeding device for two types of asymmetric parts with a truncated cone end are presented. Comparative analysis of the theoretical values of the actual feed rate of the feeding-oriented device with experimental ones showed their high convergence, which confirms the feasibility of using the proposed concept in assessing the feed rate of mechanical disk hopper feeding-oriented devices for asymmetric parts of rotation bodies.

МЕТОДОЛОГИЧЕСКИЙ ПОДХОД К ИССЛЕДОВАНИЮ И ПРОЕКТИРОВАНИЮ МЕХАНИЧЕСКИХ ДИСКОВЫХ БУНКЕРНЫХ ЗАГРУЗОЧНО-ОРИЕНТИРУЮЩИХ УСТРОЙСТВ

The article describes the main stages of research and design of mechanical disk hopper-orientating devices for asymmetric parts of rotating bodies, which make it possible to ensure the required productivity and high reliability of technological equipment based on the regularities of functioning of hopper-orientating devices. The tasks that should be solved at each stage of research and design are considered. A detailed example of the calculation, design, and investigation of an improved mechanical disk hopper feeding orientator with radial rectangular pockets, an annular orientator, and radial comb-shaped slots for a solid, frustoconical end piece is provided. The results obtained during the research and design of the improved design of the hopper feeding-orienting device made it possible to determine the ranges of operating values of the design parameters and the circumferential speed of the gripping organs, at which the device will reliably function and ensure its greatest feed rate.

An Experimental Investigation on the Forming Force in Asymmetric Parts Formed using Single Point Incremental Forming

An Experimental Investigation on the Forming Force in Asymmetric Parts Formed using Single Point Incremental Forming

Polyiodides of amino acids. Betainium triiodide

A new salt of betaine, betainium triiodide, (BetH)(I3), was synthesized and characterized using structural analysis and infrared spectroscopy. It crystallizes in the monoclinic space group C2/m with the asymmetric part containing half of the formula unit. The structure determination revealed that the betainium cation forms an (A+···A+) type centrosymmetric betainium···betainium dimeric cation with an O···O distance of 2.662(6) Å. The presence of the triiodide anion in the structure provides semiconductor properties of the resulting crystal. The bandgap for (BetH)(I3) was calculated from the electronic structure based on the crystal structure and measured from the diffuse reflectance spectrum. The results are compared with two previously known structurally characterized salts of amino acids that also contain the triiodide anion: (l-AlaH···l-Ala)(I3) and (GlyH)(I3). Thermal properties of the crystal were studied by TG and DSC methods.

Qualitative and quantitative contributions of intermolecular interactions, quantum chemical calculation, biological activity and visible-light driven photo catalysts studies of nickel complex of 4-amino-N-(5-methyl-1,3,4-thiadiazol-2-yl)benzenesulfonamide

This study reports the successful synthesis and characterization of a nickel complex of the sulfamethizole (smtz) ligand. The complex was characterized using 1H NMR and FT-IR spectroscopic analyses. The synthesized complex exhibited promising properties as a biological and visible light-driven photocatalyst. Under visible light radiation, it displayed remarkable photo-degradation capabilities, achieving a degradation efficiency of 91.2% within 80 min against a solution of methylene blue (MB) with a concentration of 10 PPM in 100 mL. To understand the complex's biological response, viscosity measurements were conducted to investigate its mode of binding with CT-DNA. The results demonstrated that the nickel complex exhibited stronger inhibitory activity and lower cytotoxicity compared to the smtz ligand, as evidenced by cytotoxic analysis and minimum inhibitory concentration (MIC) data against a range of gram-positive and gram-negative pathogens. Furthermore, the crystal structure of the complex was determined through single-crystal X-ray diffraction analysis, revealing its crystallization in the triclinic space group P-1. The asymmetric part of the unit cell consisted of a Ni0.5 metal atom, one -Picoline solvent molecule, one smtz ligand, and one coordinated water molecule. To gain further insights into the complex's properties, Hirshfeld surfaces (HS) and a 3D energy framework approach were utilized to visualize its active and inactive surfaces. The analysis indicated that the dispersion energy contribution in molecular packing was significantly greater than that of electrostatic energy. Additionally, calculations of the HOMO-LUMO energy and other quantum chemical parameters were performed to understand the molecule's stability. Overall, the synthesized nickel complex of the sulfamethizole ligand exhibited remarkable photocatalytic properties, strong inhibitory activity against pathogens, and a stable crystal structure. These findings contribute to the understanding of the complex's potential applications in photocatalysis and biomedical research.

Методика определения вероятности захвата асимметричных деталей формы тел вращения в дисковых бункерных загрузочно-ориентирующих устройствах

Modern equipment in the product assembly should be the automatically loaded reliable systems, where the hopper loading-orientation device is the main component. Recently, there appeared a lot of asymmetric parts, including those with implicit asymmetry. In this connection, it becomes necessary to design such capture devices that are optimal in all the parameters. However, the probabilistic operation principle and the device ability to operate only in capturing a specific part with certain geometric parameters significantly complicate their design and require solution to the complex multi-level tasks. The most important task is to determine its performance, namely the probability of capturing the parts in the hopper loading-orientation device. The paper presents a detailed methodology making it possible to determine the probability of capturing the parts in the bunker loading-orientation devices of various types that implement different methods in capturing and orienting parts with the revolution body shape of a wide range, both with implicit and explicit asymmetry, for constructing the performance mathematical model. To build a mathematical model of the capture probability, probabilities of finding the part in the favorable position for capturing it with its differing orientations, limiting circumferential speed of the capturing bodies of the hopper loading-orientation device and absence of interference from the interlocking parts were determined. Dependencies are provided that are making it possible to graphically determine the indicated parameters of the mathematical model

Negative Thermal Expansion in the Polymorphic Modification of Double Sulfate β-AEu(SO4)2 (A-Rb+, Cs+).

New polymorphic modifications of double sulfates β-AEu(SO4)2 (A-Rb+, Cs+) were obtained by the hydrothermal method, the structure of which differs significantly from the monoclinic modifications obtained earlier by solid-state methods. According to single-crystal diffraction data, it was found that the compounds crystallize in the orthorhombic system, space group Pnna, with parameters β-RbEu(SO4)2: a = 9.4667(4) Å, b = 13.0786(5) Å, c = 5.3760(2) Å, V = 665.61(5) Å3; β-CsEu(SO4)2: a = 9.5278(5) Å, b = 13.8385(7) Å, c = 5.3783(3) Å, V = 709.13(7) Å3. The asymmetric part of the unit cell contains one-half Rb+/Cs+ ion, one-half Eu3+ ion, both in special sites, and one SO42- ion. Both compounds exhibit nonlinear negative thermal expansion. According to the X-ray structural analysis and theoretical calculations, the polarizing effect of the alkali metal ion has a decisive influence on the demonstration of this phenomenon. Experimental indirect band gaps of β-Rb and β-Cs are 4.05 and 4.11 eV, respectively, while the direct band gaps are 4.48 and 4.54 eV, respectively. The best agreement with theoretical calculations is obtained using the ABINIT package employing PAW pseudopotentials with hybrid PBE0 functional, while norm-conserving pseudopotentials used in the frame of CASTEP code and LCAO approach in the Crystal package gave worse agreement. The properties of alkali ions also significantly affect the luminescent properties of the compounds, which leads to a strong temperature dependence of the intensity of the 5D0 → 7F4 transition in β-CsEu(SO4)2 in contrast to much weaker dependence of this kind in β-RbEu(SO4)2.

Subjective evaluation of facial asymmetry with three-dimensional simulated images among the orthodontists and laypersons: a cross-sectional study

ObjectivesWe used three-dimensional (3D) virtual images to undertake a subjective evaluation of how different factors affect the perception of facial asymmetry among orthodontists and laypersons with the aim of providing a quantitative reference for clinics.Materials and methodsA 3D virtual symmetrical facial image was acquired using FaceGen Modeller software. The left chin, mandible, lip and cheek of the virtual face were simulated in the horizontal (interior/exterior), vertical (up/down), or sagittal (forward or backward) direction in 3, 5, and 7 mm respectively with Maya software to increase asymmetry for the further subjective evaluation. A pilot study was performed among ten volunteers and 30 subjects of each group were expected to be included based on 80% sensitivity in this study. The sample size was increased by 60% to exclude incomplete and unqualified questionnaires. Eventually, a total of 48 orthodontists and 40 laypersons evaluated these images with a 10-point visual analog scale (VAS). The images were presented in random order. Each image would stop for 30 s for observers with a two-second interval between images. Asymmetry ratings and recognition accuracy for asymmetric virtual faces were analyzed to explore how different factors affect the subjective evaluation of facial asymmetry. Multivariate linear regression and multivariate logistic regression models were used for statistical data analysis.ResultsOrthodontists were found to be more critical of asymmetry than laypersons. Our results showed that observers progressively decreased ratings by 1.219 on the VAS scale and increased recognition rates by 2.301-fold as the degree of asymmetry increased by 2 mm; asymmetry in the sagittal direction was the least noticeable compared with the horizontal and vertical directions; and chin asymmetry turned out to be the most sensitive part among the four parts we simulated. Mandible asymmetry was easily confused with cheek asymmetry in the horizontal direction.ConclusionsThe degree, types and parts of asymmetry can affect ratings for facial deformity as well as the accuracy rate of identifying the asymmetrical part. Although orthodontists have higher accuracy in diagnosing asymmetrical faces than laypersons, they fail to correctly distinguish some specific asymmetrical areas.

Magnetic Field as an Important Tool in Exploring the Strongly Correlated Fermi Systems and Their Particle–Hole and Time-Reversal Asymmetries

In this review, we consider the impact of magnetic field on the properties of strongly correlated heavy-fermion compounds such as heavy-fermion metals and frustrated insulators with quantum spin liquid. Magnetic field B can be considered a universal tool, allowing the exploration of the physics controlling the remarkable properties of heavy-fermion compounds. These vivid properties are T/B scaling, exhibited under the application of magnetic field B and at fixed temperature T, and the emergence of Landau Fermi liquid behavior under the application of magnetic field. We analyze the influence of quasiparticle–hole asymmetry on the properties of heavy-fermion (HF) compounds such as the universal scaling behavior of the thermopower S/T exhibited under the application of magnetic field B. We show that universal scaling is demonstrated by different HF compounds such as β-YbAlB4, YbRh2Si2, and strongly correlated layered cobalt oxide [BiBa0.66K0.36O2]CoO2. Analyzing YbRh2Si2, we show that the T/B scaling behavior of S/T is violated at the antiferromagnetic phase (AF) transition. The residual resistivity ρ0 and the density of states N0 experience jumps at the AF transition, causing two jumps in the thermopower and its sign reversal. Our consideration is based on the flattening of the single-particle spectrum that strongly affects ρ0 and N0 and leads to the violation of particle–hole symmetry. The particle–hole asymmetry generates the asymmetrical part Δσd(V) of tunneling differential conductivity σd(V), Δσd(V)=σd(V)−σd(−V), where V is the voltage bias. We demonstrate that in the presence of magnetic field, the quasiparticle–hole asymmetry vanishes, the LFL behavior is restored, and the asymmetry disappears. Our calculations of the mentioned properties of HF compounds, based on the fermion condensation theory, are in good agreement with the experiment and support our conclusion that the fermion condensation theory is capable of describing the properties of HF compounds, including those exhibited under the application of magnetic field.

Evaluation of drug likeliness of (Z)-4-((4-hydroxy-3-methoxy benzylidene)amino)-1,5-dimethyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-one by computational analysis against coronavirus and T-cells of immune system

The Schiff base (Z)-4-((4-hydroxy-3-methoxy benzylidene)amino)-1,5-dimethyl-2-phenyl-1,2-dihydro-3H-pyrazole-3-one (VAP) has been synthesized by the condensation of 4-aminoantipyrine with vanillin and and characterized by FT-IR, 1H and 13C NMR spectroscopy. The structure of the synthesized compound has been confirmed by single-crystal X-ray diffraction studies, which shows that four units of the compound are in an asymmetric part of the crystal structure. The potential activity of synthesized Schiff base compound has been determined by molecular docking with T-cells (6bnk) and against Coronavirus (6lu7).

GENERAL SOLUTION OF THE EXCITATION PROBLEM OF A SYMMETRIC FLAT DIELECTRIC STRUCTURE BY PLANE ELECTROMAGNETIC WAVES

General solution of the excitation problem of a symmetric flat dielectric structure by two laser pulses is obtained. The symmetrical geometry consists of two dielectric prisms separated by a vacuum channel for electron acceleration (so called “sandwich”). Each prism can be illuminated with a separate laser pulse; electric filed amplitudes of pulses can differ. The general solution consist from a symmetric distribution and asymmetric one of a longitudinal electric field across the vacuum channel. In the case of a general solution, the effect of the asymmetric part on the total amplitude of the accelerating and defocusing fields is also analyzed. We determined also conditions when a symmetric or asymmetric solution only is realized. For these cases, the obtained analytical solutions are compared with results of full time-domain numerical simulations of bilateral excitation of dielectric prisms with laser pulses.

Structural, Hirshfeld surface and molecular docking studies of a new organotin(IV)-phosphoric triamide complex and an amidophosphoric acid ester proposed as possible SARS-CoV-2 and Monkeypox inhibitors

Phosphoramides and their complexes are attractive compounds due to their significant inhibiting functionality in biological medicine. In this paper, a novel organotin(IV)-phosphoramide complex (Sn(CH3)2Cl2{[(3-Cl)C6H4NH]P(O)[NC4H8O]2}2, 1), derived from a reaction between phosphoric triamide ligand with dimethyltin dichloride, and a new amidophosphoric acid ester ([OCH2C(CH3)2CH2O]P(O)[N(CH3)CH2C6H5], 2), prepared from the condensation of a cyclic chlorophosphate reagent with N-methylbenzylamine, are structurally characterized and in silico investigated as potential SARS-CoV-2 and Monkeypox inhibitors by molecular docking simulation. Both compounds crystallize in the monoclinic crystal system with space group P21/c. The asymmetric unit of the complex 1 consists of one-half molecule, where SnIV is located on an inversion center, while the asymmetric part of 2 consists of one whole molecule. In the complex 1, the tin atom adopts a six-coordinate octahedral geometry with trans groups of (Cl)2, (CH3)2 and (PO)2 (PO = phosphoric triamide ligand). The molecular architecture consists of the N–H⋯Cl hydrogen bonds stretching as a 1D linear arrangement along the b axis with intermediate R22(12) ring motifs, whereas in the case of 2, the crystal packing is devoid of any classical hydrogen bond interaction. Furthermore, a graphical analysis by using Hirshfeld surface method identifies the most important intermolecular interactions being of the type H⋯Cl/Cl⋯H (for 1) and H⋯O/O⋯H (for 1 and 2), covering the hydrogen bond interactions N–H⋯Cl and C–H⋯O═P, respectively, which turn out to be favoured. A biological molecular docking simulation on the studied compounds provides evidence to suggest a significant inhibitory potential against SARS-COV-2 (6LU7) and Monkeypox (4QWO) especially for 6LU7 with a binding energy around −6 kcal/mol competing with current effective drugs against this virus (with a binding energy around −5 and −7 kcal/mol). It is worth noting that this report is the first case of an inhibitory potential evaluation of phosphoramide compounds on Monkeypox.

Analytical Study on the Random Seismic Responses of an Asymmetrical Suspension Structure

An asymmetrical suspension structure, without vertical column support and without supplying the flexibility of spatial arrangement, is more sensitive to ground movement. The structural responses of an asymmetrical suspension structure subjected to Clough–Penzien spectrum excitation were analytically investigated in this study. First, the governing equation was decoupled into an independent state equation in generalized coordinates through the real mode decomposition method and by creatively combining it with finite element methods to acquire modal coefficients. Through the pseudo excitation method (PEM), the frequent domain solution of the dynamic response was acquired, and its power spectrum density function was then quadratically decomposed to obtain its corresponding 0–2-order spectral moments. A practical case study was performed to verify the high accuracy and computational efficiency of the proposed closed-form solution comparative to the traditional PEM. Finally, an extended analysis of the effect of the suspended span and comparisons to a normal framed structure and symmetrical suspension structures were carried out. The analysis results indicate that the larger suspended span could consume more seismic energy and result in smaller horizontal displacement and acceleration. Moreover, the comparison results also point out that the existence of the suspension part showed better seismic energy dissipation capacity compared to the normal framed structure, and two symmetrical suspension parts also performed better than a single asymmetrical part in seismic energy dissipation.

Active metamaterials for realizing odd mass density

Solids built out of active components have exhibited odd elastic stiffness tensors whose active moduli appear in the antisymmetric part and which give rise to non-Hermitian static and dynamic phenomena. Here, we present a class of active metamaterial featured with an odd mass density tensor whose asymmetric part arises from active and nonconservative forces. The odd mass density is realized using metamaterials with inner resonators connected by asymmetric and programmable feed-forward control on acceleration and active forces along the two perpendicular directions. The active forces produce unbalanced off-diagonal mass density coupling terms, leading to non-Hermiticity. The odd mass is then experimentally validated through a one-dimensional nonsymmetric wave coupling where propagating transverse waves are coupled with longitudinal ones whereas the reverse is forbidden. We reveal that the two-dimensional active metamaterials with the odd mass can perform in either energy-unbroken or energy-broken phases separated by exceptional points along principal directions of the mass density. The odd mass density contributes to the wave anisotropy in the energy-unbroken phase and directional wave energy gain in the energy-broken phase. We also numerically illustrate and experimentally demonstrate the two-dimensional wave propagation phenomena that arise from the odd mass in active solids. Finally, the existence of non-Hermitian skin effect is discussed in which boundaries host an extensive number of localized modes. It is our hope that the emergent concept of the odd mass can open up a new research platform for mechanical non-Hermitian system and pave the ways for developing next-generation wave steering devices.