I vår artikel vill vi med utgångspunkt i tröskelbegreppet (Perkins 1999) undersöka moment inom grammatiken som är svåra för studenterna att tillägna sig, men som är helt avgörande för förståelse och progression. I första hand utgår vi från en analys av underkända tentamina i ämnet svenska. Analysen pekar ut tre problemområden: svårigheter med att skilja mellan betydelse, form och funktion, med att

In this paper we explore how different ways of training communication skills can be successfully implemented in higher education, and which effects these activities may have on science students’ learning. Using content analysis, we studied a material consisting of 34 reports, written by 70 academic science teachers, as part of a teacher-training course on communication in science higher education.

A diesel engine developed for an international market must be able to run on different fuels considering the diesel fuel qualities and the increasing selection of biofuels in the world. This leads to the question of how different fuels perform relative to a standard diesel fuel when not changing the hardware settings. In this study five fuels (Japanese diesel, MK3, EN590 with 10% RME, EN590 with 3

Natural gas and hydrogen enriched natural gas has been tested as fuels together with diesel oil and RME in a single cylinder Scania research engine. The gas was introduced as port injection while the diesel was introduced as early direct injection. Because the gas was premixed with air before combustion and the diesel was injected early in the compression stroke, the engine ran close to HCCI mode.

In HCCI you do not have the same control of the combustion like in SI and Diesel engines. Controlling the start of a combustion event is a difficult task and requires feedback from previous cycles. This feedback can be retrieved from ion current measurements. By applying a voltage over the spark gap, ions will lead a current and a signal that represents the combustion in the cylinder will be retri

Utilization of an ethanol driven, combustion-based power generator promises high-efficiency combustion in diesel-like engines and avoids problems connected to shrinking supplies of fossil fuels since fuels like ethanol or dimethyl ether can be produced from renewable resources. Fuel injection into such generator through a piezoelectric micro mass flow controller (MMFC) features low power consumpti

A piezoelectric micro mass flow controller (MMFC) for liquid fuel injection into a mini-HCCI-motor for power generation is introduced. Piezoelectric actuation ensures negligible power consumption for fuel injection allowing self-sustaining operation. A pressurized fuel tank is connected to the MMFC which is designed like a normally-closed, on-/off-operating valve. Integrated piezoresistors are use

Autoignition of a homogeneous mixture is very sensitive to operating conditions, therefore fast control is necessary for reliable operation. There exists several means to control the combustion phasing of an Homogeneous Charge Compression Ignition (HCCI) engine, but most of the presented controlled HCCI result has been performed with single-input single-output controllers. In order to fully operat

Studies of relations binding ruled and ruler over the form and content of revenue assessment during the colonial era are not lacking. Rather, the intellectual challenge lies in ascertaining the degree to which the relevant economic institutions of the subjected regions in southern Asia constituted continuity of tradition, modifications thereof, or completely alien constructs. Meeting that challeng

This work has focused on studying the in-cylinder pressure fluctuations caused by rapid HCCI combustion and determine what they consist of. Inhomogeneous autoignition sets up pressure waves traversing the combustion chamber. These pressure waves induce high gas velocities which causes increased heat transfer to the walls or in worst case engine damage. In order to study the pressure fluctuations a

In this essay, we explore and discuss current practices of source critique. In our empirical analysis of a sample of interview-based studies, we find that few studies show a careful and reflective stance toward their sources. In the majority of cases, we discern a tendency to either ignore basic issues of the trustworthiness of interview material or produce technical descriptions which seem to hav

Studies on the intergenerational transmission of human capital usually assume a one-way spillover from parents to children. However, children may also affect their parents’ human capital. Using exogenous variation in education, arising from a Swedish compulsory schooling reform in the 1950s and 1960s, we address this question by studying the causal effect of children's schooling on their parents’

We examine the use of in-cylinder measurements for engine control, with emphasis on emissions control during cold start. First, the cold start emissions control problem is described. An overview of previous research in the area of in-cylinder measurements for control is presented, including sensors for pressure and other quantities. Next, analysis of cylinder pressure is described. Lastly, a cold-

This paper describes the design of a least restrictive, safe hybrid control scheme for a manufacturing transport system transporting fragile objects from a production unit to a stamping/packaging station. The control scheme consists of several control modes. One control mode handles trajectory following using time-optimal control, the other control modes are safety related and are engaged in a lea

We analyze the effects of the increase in China’s import competition on Mexican domestic and international migration. We exploit the variation in exposure to competition from China, following its accession to the WTO in 2001, across Mexican municipalities and estimate the effect of international competition on the individual decision to migrate. Controlling for individual and municipality features