COVID-19 as Industry Forcing Function: Challenges for Entrepreneurship in the Post-Pandemic Future

The COVID-19 crisis has changed how firms and industries do business – at least for now. What is uncertain, however, is the duration of that change. Will the industry change induced by the COVID-19 crisis persist and, if so, for how long? Can a crisis, and particularly the COVID-19 crisis, act as a more permanent change agent and create an environment that mimics the entrepreneurial opportunity that industry forcing functions create? If yes, then there is cause to consider the entrepreneurial opportunity that the COVID-19 crisis provides. In this paper, we review the changes that the pandemic has brought to business practices. Furthermore, we discuss the differences between crisis-based opportunity and entrepreneurial opportunity created by industry forcing functions in order to illuminate the ability of a COVID-19 crisis–induced Low Touch Economy to sustainably create entrepreneurial opportunities. We show examples and list the attributes of industry forcing functions that have already provided sustainable entrepreneurial opportunity. Then, we match these attributes with the factors pertaining to the COVID-19-related Low Touch Economy. We find that the COVID-19 crisis has similarities and differences to the traditional industry forcing functions started by disruptive technologies. However, unlike traditional industry forcing functions, the COVID-19 crisis acts in a pan-industrial manner, making the impact of the pandemic more profound. Furthermore, the timing of the pandemic is important too: the COVID-19 crisis struck during the emergence of a Schumpeterian wave of Industry 4.0 and accelerated the adoption of its most important harbingers. We provide researchers and practitioners a lens through which to review not only the COVID-19 crisis’s possibility of lasting effects, but also how it will affect entrepreneurs.

Inhomogeneous Airy’s and Generalized Airy’s Equations with Initial and Bounday Conditions

Inhomogeneous Airy’s and Generalized Airy’s equations with initial and boundary date are considered in this work. Solutions are obtained for constant and variable forcing functions, and general solutions are expressed in terms of Standard and Generalized Nield-Kuznetsov functions of the first- and second-kinds. Series representations of these functions and their efficient computation methodologies are presented with examples.

Accounting for Circumferential Flow Nonuniformity in a Multi-Stage Axial Compressor

The flow field in a compressor is circumferentially non-uniform due to geometric imperfections, inlet flow nonuniformities, and blade row interactions. Therefore, the flow field, as represented by measurements from discrete stationary instrumentation, can be skewed and contribute to uncertainties in both calculated one-dimensional performance parameters and aerodynamic forcing functions needed for aeromechanics analyses. Considering this challenge, this paper documents a continued effort to account for compressor circumferential flow nonuniformities based on discrete, under-sampled measurements. First, the total pressure field downstream of the first two stators in a three-stage axial compressor was measured across half of the annulus. The circumferential nonuniformities in the stator exit flow, including vane wake variability, were characterized. In addition, the influence of wake variation on stage performance calculations and aerodynamic forcing functions were investigated. In the present study for the compressor with an approximate pressure ratio of 1.3 at design point, the circumferential nonuniformity in total pressure yields an approximate 2.4-point variation in isentropic efficiency and 54% variation in spectral magnitudes of the fundamental forcing frequency for the embedded stage. Furthermore, the stator exit circumferential flow nonuniformity is accounted for by reconstructing the full-annulus flow using a novel multi-wavelet approximation method. Strong agreement was achieved between experiment and the reconstructed total pressure field from a small segment of measurements representing 20% coverage of the annulus. Analysis shows the wake-wake interactions from the upstream vane rows dominate the circumferentially nonuniform distributions in the total pressure field downstream of stators. The features associated with wake-wake interactions accounting for passage-to-passage variations are resolved in the reconstructed total pressure profile, yielding representative mean flow properties and aerodynamic forcing functions.

Statistics of Voltage Processes in Random Environment

A method is developed to characterize the performance of voltage processes X(t) harvested from primary-absorber dynamical systems subjected to Gaussian forcing functions. The method is based on properties of the Slepian model of X(t) and Monte Carlo simulation. Statistics are calculated for excursions of X(t) above levels which can be related to energy demand. The duration and the area of these excursions are used as metrics for the voltage process. Their statistics depend on the topology and the parameters of primary-absorber dynamical systems, which can be optimized to maximize the output voltage.

Flow-Induced Vibration Analysis of Topside Piping at High Pressure

Flow-induced vibration (FIV) from high-velocity multiphase flow is a common source of vibration concern in process piping, potentially leading to fatigue failures and hydrocarbon leaks. A combination of computational fluid dynamics (CFD) and finite element (FE) modeling offers a potentially powerful tool for assessing and diagnosing multi-phase FIV problems in hydrocarbon-production piping systems. Global energy consultancy Xodus Group performed FIV studies on an Equinor-operated topside production system, carrying multiphase flow at high-pressure (approximately 69 bara) conditions, where significant vibration was measured. The study assessed different vibration-simulation methodologies, combining FE analysis with forcing functions based on both correlations and CFD simulations. The aim was to gain a better understanding of the accuracy and limitations of calculation methods typically used to assess fatigue. Calculating Multiphase FIV in Operational Pipework While CFD FIV modeling methods have been well validated against low-pressure water-airflow under laboratory conditions (Emmerson et al. 2016a and 2016b), little has been published to show how well these techniques perform for operational hydrocarbon-production systems. As these systems usually operate at higher pressures with complex, live hydrocarbon fluids and water, the process conditions are often not well defined. They typically incorporate sev-eral features that could complicate the vibration-generation mechanisms such as long upstream pipelines, chokes, and convoluted combinations of pipe bends with complex support arrangements. As part of the development of a new Energy Institute guidance document for subsea pipework, the project with Equinor was instigated following a joint industry project (JIP) established by Xodus, in collaboration with TNO and funded by six major operators, to improve techniques for estimating forcing functions in liquid-gas flows. Vibration measurements were taken at various locations on a section of piping carrying multiphase flow at high-pressure conditions (approximately 69 bara) (Fig. 1). The forces were applied in harmonic, transient, and fluid structural interaction (FSI) simulations (directly coupled FE and CFD). The topside piping arrangement consists of 16-in. schedule-100 piping, with a tee at the top of a riser section followed by six 90° and four 45° 1.5 R/D elbows and is reasonably well supported (as shown in Fig. 1). The measurements provided the vibration velocity of the piping structure, and frequency spectra analysis was performed for comparison with the structural-response simulations. The main locations of interest are V4 and V5 as the measured vibration was the highest here. The peak vibration velocity at V4 is 4.7 mm/s and this occurs at 5.1 Hz in the EW-Y direction (Fig. 2), while at V5 the peak is 6.4 mm/s at 5.2 Hz.

Selection Methodology of an Electric Actuator for Nose Landing Gear of a Light Weight Aircraft

Landing gear system of an aircraft enables it to take off and land with safety and comfort. Because of the horizontal and vertical velocity of aircraft, upon landing, the complete aircraft undergoes different forcing functions in the form of the impact force that is absorbed by landing gears, shock absorbers, and actuators. In this research, a selection methodology has been proposed for an electrical actuator to be installed in the retraction mechanism of nose landing gear of an aircraft having 1600 kg gross takeoff weight. Nose landing gear and its associated components, like strut and shock absorbers, were modeled in CAD software. Analytical expressions were then developed in order to calculate the actuator stroke, translational velocity, force, and power for complete cycle of retraction, and some were subsequently compared with the computational results that were obtained using MSC ADAMS®. Air in the oleo-pneumatic shock absorber of nose landing gear was modeled as a nonlinear spring with equivalent spring constant, whereas hydraulic oil was modeled as a nonlinear damper with equivalent damping constant. The nose landing gear system was modeled as a mass-spring-damper system for which a solution for sinusoidal forcing functions is proposed. Finally, an electrical actuator has been selected, which can retract and extend nose landing gear, meeting all of the constraints of aircraft, like fuselage space, aircraft ground clearance, locking loads, power consumption, retraction and extension time, and dynamic response of aircraft. It was found that the selection of an electrical actuator is based upon the quantification of forces transmitted to electrical actuator during one point load at gross takeoff weight. The ability of retraction and extension time, as dictated by Federal Aviation Regulation, has also been given due consideration in the proposed methodology as significant criteria. The proposed system is now in the process of ground testing, followed by flight testing in the near future.

Nonlinear Dynamics of Swinging Clapper Bells under Arbitrary or Resonant Forcing Functions

Study of swinging clapper bells involves aspects encompassing sound and acoustic engineering, mechanical engineering, and structural engineering. From the musical point of view, clapper bells are directly played idiophone instruments, where the playing device, the clapper, although directly excited, is not explicitly controlled by the bell ringer. The achievement of a clear and optimal sound mainly depends on the acoustic characteristics of the bell and on the regularity of the clapper strokes, which is not only governed by the ringing style and the relevant parameters of clapper and bell but also by the real time corrections to the excitation introduced by trained bell ringers. In fact, despite centuries of experience allowed to optimize the bell performances, standardizing proportions and mounting arrangements, effective sound control requires some fine tuning of the forcing function. Another crucial topic, especially in view of assessing existing structures, regards the evaluation of time histories of the actions transmitted by the bell to the pivots and the study of the interactions between the bell and the supporting structures, belfries, and bell-towers. “Ringability” of swinging bells and bell-structure interactions are usually tackled in the framework of rigid body dynamics, so arriving at an initial value problem, governed by a system of two second order nonlinear ordinary differential equations (ODEs), whose solutions are piecewise-defined functions. In the relevant literature, numerical solutions of the system are commonly sought using built-in algorithms provided in advanced software packages; since the use of such general algorithms is subject to some restrictions, especially regarding the forcing functions, validity of the results is often limited. The present study focuses on an innovative procedure to solve the equations of motion. The method, extremely fast and effective, is based on original numerical explicit-implicit predictor-corrector integration algorithms with constant time step, duly validated reproducing the outcomes of relevant reference case studies. Each time the clapper strikes the bell a new “piece” of the solution is initialized, so avoiding user interventions in the elaboration phase. Independently on the oscillation amplitude and on the duration of the considered time interval, the algorithms can successfully manage undamped oscillations; friction and viscosity damped oscillations; free oscillations in transient and stationary phases; and can be applied also to solve stiff equations. Furthermore, the capability of the proposed methods to deal with arbitrary forcing functions is particularly innovative. The outcomes of relevant case studies, regarding the oscillations of the old tenor bell of the Great St. Mary church in Cambridge, confirm the potentialities of the method, also highlighting some topical issues, involving, for example, the assessment of damping equivalence. Finally, a pioneering feature of the algorithms is their ability to handle and to define “resonant” forcing functions, continuously tuning the frequency of the excitation to the natural frequency of the oscillation, according to the oscillation amplitude.