Repentance as Rebuke: Betrayal and Moral Injury in Safety Engineering

Following other contributions about the MAX accidents to this journal, this paper explores the role of betrayal and moral injury in safety engineering related to the U.S. federal regulator’s role in approving the Boeing 737MAX—a plane involved in two crashes that together killed 346 people. It discusses the tension between humility and hubris...

The maximum efficiency of nano heat engines depends on more than temperature

Sadi Carnot's theorem regarding the maximum efficiency of heat engines is considered to be of fundamental importance in thermodynamics. This theorem famously states that the maximum efficiency depends only on the temperature of the heat baths used by the engine, but not on the specific structure of baths. Here, we show that when the heat...

A Global Assessment of Runoff Sensitivity to Changes in Precipitation, Potential Evaporation, and Other Factors

Precipitation (P) and potential evaporation (E_p) are commonly studied drivers of changing freshwater availability, as aridity (E_p/P) explains ∼90% of the spatial differences in mean runoff across the globe. However, it is unclear if changes in aridity over time are also the most important cause for temporal changes in...

Reconciling food security and bioenergy: Priorities for action

Understanding the complex interactions among food security, bioenergy sustainability, and resource management requires a focus on specific contextual problems and opportunities. The United Nations' 2030 Sustainable Development Goals place a high priority on food and energy security; bioenergy plays an important role in achieving both goals....

Scaling, similarity, and the fourth paradigm for hydrology

In this synthesis paper addressing hydrologic scaling and similarity, we posit that roadblocks in the search for universal laws of hydrology are hindered by our focus on computational simulation (the third paradigm) and assert that it is time for hydrology to embrace a fourth paradigm of data-intensive science. Advances in information-based...

Autonomous quantum clocks: Does thermodynamics limit our ability to measure time?

Time remains one of the least well-understood concepts in physics, most notably in quantum mechanics. A central goal is to find the fundamental limits of measuring time. One of the main obstacles is the fact that time is not an observable and thus has to be measured indirectly. Here, we explore these questions by introducing a model of time...

Dynamical maps, quantum detailed balance, and the Petz recovery map

Markovian master equations (formally known as quantum dynamical semigroups) can be used to describe the evolution of a quantum state ρ when in contact with a memoryless thermal bath. This approach has had much success in describing the dynamics of real-life open quantum systems in the laboratory. Such dynamics increase the entropy of the...

Surpassing the Carnot efficiency by extracting imperfect work

A suitable way of quantifying work for microscopic quantum systems has been constantly debated in the field of quantum thermodynamics. One natural approach is to measure the average increase in energy of an ancillary system, called the battery, after a work extraction protocol. The quality of energy extracted is usually argued to be good by...

Dynamical error bounds for continuum discretisation via Gauss quadrature rules-A Lieb-Robinson bound approach

Instances of discrete quantum systems coupled to a continuum of oscillators are ubiquitous in physics. Often the continua are approximated by a discrete set of modes. We derive error bounds on expectation values of system observables that have been time evolved under such discretised Hamiltonians. These bounds take on the form of a function...

Patterns of similarity of seasonal water balances: A window into streamflow variability over a range of time scales

Recent hydrologic synthesis efforts have presented evidence that the seasonal water balance is at the core of overall catchment responses, and understanding it will assist in predicting signatures of streamflow variability at other time scales, including interannual variability, the flow duration curve, low flows, and floods. In this study, we...

An analytical model for soil-atmosphere feedback

Soil-atmosphere feedback is a key for understanding the hydrological cycle and the direction of potential system changes. This paper presents an analytical framework to study the interplay between soil and atmospheric moisture, using as input only the boundary conditions at the upstream end of trajectory, assuming advective moisture transport...

The role of ambiguity in the art and science of yacht design

Development of a dual service rescue and lifeboat

Shell's 84.000 DWT crude/product tankers

The forces on a compression surface based on an axisymmetrical conical flow field

Formulae are derived for calculating the lift, drag and pitching moment on a surface based on an axisymmetrical conical flow field (a "Jones wing"). They involve in each case the numerical integration of functions of one variable, and are therefore in forms convenient for machine computation. Results obtained using the formulae in an...

The supersonic flow past a circular cone at incidence

The problem of calculating the supersonic flow past a circular cone at small incidence alpha is treated by the method of inner and outer expansions, on the assumption that it can be expressed as a perturbation (in powers of a) of the corresponding axially symmetric flow. Stone' s first order solution, and the first-order vortical layer solution...

The construction of a compression surface based on an axisymmetrical conical flow field

A method is given for constructing compression surfaces using the flow field behind an axisymmetrical conical shock wave (suggested by Jones). The construction may be either direct (starting from a prescribed leading edge) or inverse (starting from a prescribed trailing edge) and in the former case employs only direct calculation using available...

A linearized investigation of the effect of a wall boundary layer on the motion of a reflected shock

A linearized treatment is given of boundary-layer effects on the reflection of a shock wave at the closed end of a tube. The velocity af the reflected shock and the pressure behind it are perturbed (a) by the flow non-uniformity caused in the initial shock tube flow by boundary layer growth and shock attenuation, and (b) by the effect of the...